Signalman: Round the Mulberry Bush : White to Play

A sweet problem that feels, initially, that its not quite resolvable, until you see the issues in the defence for Black.

I saw the problem with the Bishop interposition quite early, but it took me another set of calculations to see why interposing the Queen is also a failure.

It always intriguing to see what line the computer will choose, and in this case it went for the game line.