f5! - Dutch!
It's a safe assumption that if he played 1.c4, then he wants to fianchetto the L.S. bishop, so the Tony Miles - 1...b6 is annoying for him. (he can still do it, by Nf3, g3, Bg2, but then his Nf3 "cannot" move - for the Bg2 is his main power piece so one piece of yours (Bb7) controls 2 pieces of his - Bg2, Nf3, no? my opinion).
d6 is annoying, but tolerable.
(I'm playing 1.c4 for about 2 months now).
Nf6.then probably Nc3 would be played then e6 is the best..ready for the pin in b4..I guess this is the best reply.