In the Michael Oldfield book there is a picture of Clapton with End Bucknell, attending one of the Wembley Arena 1982 shows.
Clapton joined MK on stage at Hammersmith December 1985 concerts, at least the 19th and I think 22nd.
Then Princes Trust 1986 at Wembley Arena, and after that Mk joined Clapton band for some concerts in the UK, Paris, Brussels and maybe some more, then a full tour in 1988 and some RAH dates in 1989, while MK was composing Last Exit to Brooklyn score at home with Guy.
In his biography it just mention that MK was in his band for the 1988 tour, just mention, like if MK was just another random musician hired for the tour.