I was astonished, on coming to watch this episode recently, to find I had no recollection of it at all, even though I am sure I have watched all the way through the Studio Canal box set of the remaining episodes of Series 1 & the whole of Series 2. I suspect this may be because it shares a disc with the other remaining complete episode, The Frighteners, which is an excellent episode & may have distracted me from this when playing the disc. Of course the reason The Frighteners was treated as the 'only' series 1 episode in existence is that it was, until Girl on the Trapeze was rediscovered in 2001, being seen for the first time at the Missing Believed Wiped event in 2002.
Of course I put it on in anticipation of Big Finish's release of the missing first series episodes as audio recordings, staring January. Girl on a Trapeze suffers in two other ways in comparison to The Frighteners. Up until recently there has been a received wisdom among Avengers-philes that The Frighteners was the best of a mediocre lot, & the almost complete wiping of the rest of the series was no great loss. This is plainly not the case, even going by the episode reconstructions on the box set.
Rather the other way Girl on a Trapeze misses out may be more valid for some fans: there is no Steed in it (although he appears in the credits), & these first series episodes are *very* different from, say, those with Mrs Peel. I don't mind the absence of Steed myself, since it accentuates that this episode is in a different class of television: much darker, more gritty, full of almost film noir visuals. It feels like being a traitor to say this, but I don't even mind Steed being played by someone other than Patrick Macnee, as he is in the South African radio serials.
To me this serves to emphasise the differing role of Steed over the years, also mirrored by the relative organisation & Establishment position of The Avengers as the series progress. The Avengers start off with a completely amateur doctor as the key figure, with the shadowy & vaguely disreputable figure of Steed as a sidekick, to the organised role of Steed the father figure to Miss King in series 6 (& almost to Grand Old Man status in The New Avengers).
I think the major difference between these series 1 episodes & the later ones is actually that they are set in the real world: I feel the Avengers truism that Avengersland was self-consciously unreal may only be true of later series. In this episode the real world of a circus - of the time - is an excellent visual setting for this episode. Of course this real-world setting makes the episode creak like an old gate, fifty years later. In fact it feels different from most later Avengers episodes, at least in the beginning, much more like a police procedural.
Dr Keel's accidental status as an Avenger is critical here, that he gets caught up in the aftermath of a suicide, while on his way out for the evening. His professional involvement is what fortuitously draws him in. It is also apparently pure nosiness that makes him pursue the trail of the dead woman to the circus, since the police are pursuing their investigation at the same time.
My conclusion on this episode is that I don't mind it at all, despite it having virtually none of the characteristic eccentric Avengers touches. As a TV play, it is superb, paced exactly right, with good characterisation & wonderful visuals courtesy of the circus. I can't wait for the Big Finish audio remakes to come out!