Going back several posts to the "authenticity" of the Royal Ballet's Swan Lake, one thing to note is that the choreography of the first act pas de trois was substantially changed for this production. Dowell brought in Irina Jacobsen to help with the staging and so this number is now very much "fancier" than the version originally done by the Sadler's Wells/Royal Ballet.
And I'm pretty sure that there have also been changes to the second act - even leaving aside the omission of Benno. I'm fairly sure there have been changes to the choroegraphy for the "big" swans and as we no longer have the huntsmen supporting the corps de ballet swans, there are obviously changes there.
There have also been some minor changes to the choreography of the last act making it more elaborate. But here the story always was that there was a gap in the notation which de Valois filled. However, I also remember being told that the missing part was only a matter of around a minute or so.
I first saw the Royal Ballet Swan Lake back in in the 1950's and there have been constant changes in all the productions since then. Dowell's version I find particularly unattractive; wrong-headed designs, rudeness, drunkeness and no sense of classical style. I couldn't say whether it is the most "authentic" version on the stage today, but I can state from my own observation that it has changed considerably in the past 50 years.
As far as I know, the Sadler's Wells four act 1934 production changed little if at all until 1952 when de Valois revised the production with Ashton choreographing a pas de six to the Act I Valse and in Act III a new version of the Neapolitan Dance in Act III.
In 1963 a major revision took place with added theatrical inventions by Robert Helpmann and the four acts becoming three including a Prologue, with various choreographic contributions by; Ashton, Nureyev and
Maria Fay (too many details to remember and list) but including a major revision of Act four with imaginative patterning for the corps which could only really be seen to best effect from the balcony or amphitheatre.
In 1965 the Royal Ballet Touring Company gave a new production going back to the atmospheric Leslie Hurry designs staged by John Field and Ashton which was performed at the Royal Opera House.
In 1971 The main Royal Ballet adopted the Touring Company version but not so long after Ashtons last act was dropped and Ivanov's restored, Petipa's Pas de trois was also restored to Act I and the Ashton's Pas de quatre moved to Act III.
Norman Morrice staged another production in 1979 in which I think some dances reverted to earlier amendations.
1987 Anthony Dowell production which later included Ashton's Neapolitan dance.
I was interested to read Jane Simpson's comment on the film of Dame Margot and Michael Somes. The described unsupported hops were a shock to me as I had never seen them or remembered if that is the excerpt on the film which also included "The Firebird" I saw decades ago.
I am not at home so cannot be exact but I hope not too far wrong as I wrote a history of Swan Lake for my own use sometime ago and know the productions well.