Michael George Doubell, a grandson of the Michael George to settle the family in South Africa, performed as a Strongman.
"Michael George joined Filis' circus as a 'Strong Man' and performed at Earls Court in 1899. While in London, he married Sarah Ann Tant age 22 of 22 Pembroke Mews, London. This marriage took place on 25 Feb 1900 at St Philips, Kensington. Her father was Charles Tant," according to Millicent Emslie - http://archiver.rootsweb.ancestry.com/th/read/DOUBELL/2002-09/10328...
While there are numerous grandsons of the SV/PROG named Michael George, I suspect that the Strongman was a son of Thomas Henry Doubell (1837 - 1909) and Caroline Elizabeth Magdalena Myburgh (1837 - 1920). Ancestry.com has the marriage record for a Michael George Doubell and Sarah Ann Tant that gives his father's name as Thomas.
Frank Fillis came to South Africa in 1880 to join the circus of W.H. Bell, eventually taking over when Bell died; Ancestry24.com has a good summary of Fillis attractions in Cape Town and Johannesburg - ancestry24.com/were-your-ancestors-in-the-circus/
In 1899 - 1900 Fillis "took an extraordinary show entitled "Savage South Africa" to England, but despite the attraction of an authentic South African stagecoach, black warriors and other novelties, it failed and he was again bankrupt." This was presumably the show at which Michael George performed as a Strongman.
ColonialFilm.org.uk has video of the troupe's arrival in Southampton - http://www.colonialfilm.org.uk/node/1186 . "From Southampton, ‘the natives and animals’ travelled on ‘three special trains’ to Earls Court, where they performed twice daily at the Empress Theatre as part of the Greater Britain Exhibition"
However, I have not yet found any references to Michael George Doubell, or a Strongman, in connection with Fillis' circus.