Notting Hill Carnival is most decidedly a major black folkloric event, and very welcoming to white people as well, taking part as well as watching. And then you have samba bands turning up and taking key roles in, for example the Strawberry Fair in Cambridge in June (where I always feel they end up looking and moving remarkably like Morris Dancers...)

I haven't seen any Morris Dancers at Notting Hill Carnival, but it can only a matter of time.

And in this article about the origins of Carnival in Trinidada there is a mention of "the performance by blacks of British mummers' plays and other Christmas customs."

And a more modern referance to Mummers in the West Indies is included in this site about Banbury Hobby Horse Festival in 2003 - "A highlight was a performance of a play based on the 'Mum and Tuk' mummers plays from the West Indies put on by a school from Gloucester." (And here is some more about that.)