I hadn't realised until a few minutes ago, but the Wintershall Estate are again peforming the Passion in Trafalgar Square this Good Friday.
I went to what they termed the "rehearsal" last year. It was a very rewarding experience, and quite brilliant for children. Last year it had the nature of a "promenade" performance, so the audience could follow part of the action round the square - this is what makes it fun for children.
This year there are two performances, one at 12 noon and the second at 3.15 pm.
Details here: highly recommended.