"The Traveller" as a series sounds reminiscent of "Doctor Who," with its titular character having adventures across time and space, and the mention of the "6th Traveller" seems to be an allusion to the Sixth Doctor, portrayed by Colin Baker in the British science fiction series. Since "The Traveller" is not a known established series outside of this reference, we can only speculate or create a fictional backstory based on the analogy to "Doctor Who." In the hypothetical scenario where "The Traveller" series follows a similar structure to "Doctor Who," the 6th Traveller might be a character who, like Colin Baker's portrayal of the Doctor, is more flamboyant, brash, and sometimes more unpredictable or unstable than previous incarnations. This character could be known for her eccentric clothing choices, a sharp contrast to the other, perhaps more subdued, versions of the Traveller. If the 6th Traveller's character was to mirror the Sixth Doctor's tenure, her story arcs might involve dealing with the consequences left behind by her previous incarnations, facing off against old and new foes, and challenging complex moral dilemmas. Furthermore, her personality could have distinctively alien or non-human traits, coming across as conceited or self-assured yet still retaining a core of compassion and a strong moral compass. In the "Doctor Who" series, the Sixth Doctor's tenure was notably rocky, with mixed reactions from fans and a troubled production behind the scenes. Therefore, if "The Traveller" series paralleled this, the 6th Traveller's era might also be marred by controversy, script issues, and fan division, potentially leading to a truncated run compared to other Travellers. Without further information or an actual series called "The Traveller" to reference, this remains purely speculative and serves as a creative interpretation of the question posed.

If we are fantasizing about a hypothetical "The Traveller" series in the vein of "Doctor Who," and considering the Sixth Doctor was portrayed by Colin Baker, it would be interesting to think of an actress from that era (mid-1980s) who could have filled the role of the 6th Traveller in a similar style. Given the parameters of the question (having adventures in time and space in her "old-lady"), the actress might be someone who was in her middle age or could convincingly play an older character during that time period. Here are a few options: 1. **Maggie Smith** - An accomplished actress with a broad range, known for both her dramatic and comedic roles. By the mid-80s, she already had several notable performances and could bring a touch of class and depth to the character of the 6th Traveller. 2. **Dame Diana Rigg** - Famous for her role as Emma Peel in "The Avengers" TV series in the 1960s, Diana Rigg was a versatile actress who could portray strength, intelligence, and eccentricity. 3. **Helen Mirren** - Though not quite "old" in the mid-80s, Helen Mirren has always carried a sense of gravitas and authority that could translate well into a time-traveling adventurer. 4. **Meryl Streep** - Although American, Meryl Streep's exceptional adaptability and her capacity for accents could have made her a captivating 6th Traveller. 5. **Judi Dench** - By the mid-80s, Dame Judi Dench was a well-respected actress with a commanding presence, able to convey complexity and a sharp wit. Remember, this is purely speculative, as there is no actual series known as "The Traveller" to reference. Casting would depend on many factors, including the creative direction of the show, network decisions, and the actress's interest and availability.

Given that Diana Rigg hypothetically filled the role of the 3rd Traveller, let's consider other British actresses who could have played the 6th Traveller, in line with more mid-level fame comparable to Colin Baker before he took on his role as the Doctor. 1. **Linda Bellingham** - Known for her role as the mother in the Oxo family television adverts in the UK, as well as extensive work in television drama, Linda Bellingham could have brought a warm and relatable presence to the role while also being capable of showcasing the more assertive attributes that might be required for a time-traveling adventurer. 2. **Felicity Kendal** - As a beloved television actress, particularly known for "The Good Life," Felicity Kendal's charm and comedic timing could bring a lighter, more compassionate touch to the role of the 6th Traveller, which would be a stark contrast to the more bombastic portrayal by her predecessor. 3. **Penelope Keith** - Recognized for her leading roles in popular British sitcoms such as "To the Manor Born" and "The Good Life" (alongside Felicity Kendal), Penelope Keith's eminent poise and commanding screen presence could have allowed her to capture a 6th Traveller with authority and intellect, reminiscent of the commanding nature that Colin Baker aimed to achieve. Each actress would bring a unique flavor to the role, and their interpretation of the 6th Traveller would have been shaped by their respective acting strengths and personalities, which could have left a distinct mark on the hypothetical science fiction show, "The Traveller."

If we're contending with a "The Traveller" series where Penelope Keith hypothetically succeeded Joanna Lumley's 5th Traveller, we have an intriguing progression of characterizations. Keith's portrayal might be characterized by a greater sense of authority and assertiveness, akin to how Colin Baker's Sixth Doctor contrasted with Peter Davison's Fifth Doctor in the actual "Doctor Who" series. Joanna Lumley, having a background with roles like Sapphire in "Sapphire & Steel," would likely have brought an ethereal, charismatic quality to the 5th Traveller. Her incarnation could have been gentle yet resilient, with an air of mystery and sophistication. Following Lumley's softer portrayal, Penelope Keith's 6th Traveller would potentially capitalize on her capacity for strong-willed and sometimes formidable characters, as she famously did in her sitcom roles. The 6th Traveller under Keith's stewardship might appear more daunting, with an aristocratic bearing that commands respect, yet maintaining an undercurrent of warmth and humor. This change in demeanor could lead to a more confrontational and challenging character, adding new dynamics and tensions in the narrative and with companions. Despite any mixed reactions from fans--similar to those received by Colin Baker due to the stark contrast he presented after Davison's portrayal--Keith's 6th Traveller may have offered a fresh, distinctive take on the titular character. Such a change can invigorate a series, deepening the lore and pushing the protagonist into uncharted territory, both personally and in the realms of time and space. The evolution of the character, from Lumley's nuanced and approachable 5th Traveller to Keith's more commanding 6th Traveller, mirrors the ebb and flow of personalities seen in the succession of the various incarnations of "Doctor Who's" Doctor. An audience could expect to see interesting story arcs that highlight this shift and challenge the 6th Traveller in new ways, leveraging Keith's strengths to further develop the show's universe.

In this imagined "Traveller" universe, it seems Penelope Keith's 6th Traveller faced a similar challenge to Colin Baker's Sixth Doctor, whose tenure was also cut short and whose final season--the "Trial of a Time Lord" arc--received mixed reviews. The Tribunal arc, with an ensemble of Helen Mirren, Maggie Smith, and Glenda Jackson as members of the Tribunal, would certainly have been a remarkable event. All three are acclaimed actresses with formidable stage and screen presence, experienced in Shakespeare and with the ability to imbue even the most fantastical of lines with gravitas and conviction. The concept of having such talent on screen is quite exciting, but it appears that the execution was less successful in this hypothetical series. With the arc being described as "an almighty mess," this suggests there were likely issues with the storyline, pacing, or coherence of the Tribunal's trial process. Perhaps the series attempted to tackle overly ambitious themes or suffered from convoluted plots that didn't quite resonate with the fans. The writing might not have done justice to the significant talents of the actresses involved, leading to a disconnect between viewers' expectations and the resulting storyline. The discomfort of trying to "keep a straight face" could indicate that the material was challenging to perform authentically, possibly due to incongruencies in the script or a lack of serious engagement with the story's stakes. Unfortunately, such missteps are not uncommon in science fiction television, where high-concept ideas sometimes outpace the narrative structure or available production resources. These are often further complicated by the pressures of maintaining high ratings and audience engagement, which can lead to rushed or ill-considered creative decisions. Despite the faults of the Tribunal arc, the two seasons with Penelope Keith as the 6th Traveller may have had their highlights and could still be remembered fondly by a segment of the fanbase. In the "Doctor Who" fandom, for instance, every Doctor, irrespective of the controversial aspects of their time on the show, has their supporters and is often re-evaluated positively in hindsight. Similarly, in this hypothetical "Traveller" series, Keith's era might gain a cult following or receive a more favorable re-appraisal over time, especially for the moments when it shone.

Given the obvious parallel to "Doctor Who" and its audio range produced by Big Finish (akin to your reference to "Small Start" audios), it's quite possible that in this hypothetical "Traveller" universe, Penelope Keith's 6th Traveller could have seen a renaissance or gained newfound appreciation through audio dramas. Audio dramas offer a unique medium that can sometimes circumvent the issues faced on television, such as budget constraints and visual effects. They allow for more expansive storytelling and the exploration of complex narratives that may not have translated well to the screen. Moreover, audio dramas can focus on character development and delve deeper into existing lore without the same level of visual distraction. If Keith's 6th Traveller was better received in the "Small Start" audio dramas, it could be for several reasons: 1. **Better Scripting**: With a different set of writers or more time to develop stories, the quality of writing in the audio dramas may have been higher, offering a more consistent and engaging narrative experience. 2. **Freedom of Imagination**: Audio plays often engage the audience's imagination more directly than visual media, allowing listeners to create their own mental images of the characters and settings. 3. **Acting Prowess**: Penelope Keith and other talented voice actors might have been able to bring more nuance to their performances without the limitations of special effects or costume, further endearing the 6th Traveller to fans. 4. **Continued Development**: The audio format allows for further development of the character of the Traveller, often revealing sides of her character not seen on television. 5. **Fan Re-engagement**: For fans who were dissatisfied with the Tribunal arc on television, the audio dramas could offer redemption and a chance to re-engage with the character of the 6th Traveller in more satisfying storylines. In our real world, "Doctor Who" audio stories have indeed been a boon for certain iterations of the Doctor whose television time was limited, such as Paul McGann's Eighth Doctor, who has become beloved partly due to his extensive audio drama catalog. Similarly, in the Traveller's universe, Keith's iteration might gain a robust following through audio stories, allowing her character to receive the depth and appreciation that may have been lacking on the small screen itself.

In this reimagined "Traveller" narrative, it's fascinating to see elements that both diverge from and parallel the history of "Doctor Who." The dignified exit for Penelope Keith's 6th Traveller contrasts with the untimely conclusion of Colin Baker's tenure as the Sixth Doctor. The intricate final showdown with "the Auditor of Darkness," with its mix of character drama and high stakes, provides a storybook end to the 6th Traveller's journey. The scenario you've described offers a rich tapestry for the series lore. Utilizing the opaque transition period between Keith's Traveller and the Lansbury era is a creative way to expand the universe of "The Traveller," much like the fan-fiction and audio drama expansions within "Doctor Who." In the "Doctor Who" fandom, the lack of an on-screen regeneration from Sixth to Seventh Doctor inspired a range of fan theories and stories to fill in the gaps. Similarly, the absence of a full on-screen regeneration for the 6th Traveller, merely a fade to white, gives fans and creators alike a space to construct their own narratives about what happened to Keith's Traveller after absorbing the Auditor of Darkness's malevolence. The concept of 22-Beta theories provides an open canvas for fan works and Small Start audios, allowing them to present alternate versions of the Traveller or what could be multi-dimensional echoes of the same character. This is a pleasing nod to the "Doctor Who" expanded universe, where "unbound" stories and alternative versions of the Doctor are explored. Regarding the Lansbury era, the careful avoidance of direct confirmation of her as the 7th incarnation maintains an element of mystery and opens the door to countless possibilities. This echoes the "Curse of Fatal Death" comic relief sketch and the "War Doctor" story arc from "Doctor Who," blurring the lines across the chronological order of the Travellers or Doctors and giving freedom to explore "what if" scenarios that challenge the conventions of the Traveller's regenerations. This intricate universe is exemplified by the legacy that each version of the Traveller leaves behind: a blend of television, audio, and fan fiction contribute layers to the character's mythology. The nuanced approach to continuity and regeneration taken by "The Traveller" and used by subsequent writers allows for a versatile and ever-expanding storyline that echoes the timeless appeal of series like "Doctor Who." Such flexibility accommodates new creators and fan engagement, ensuring the enduring legacy of the series within its passionate community.