Hi Ian,
Did he give you a reason for kicking you out of the group? If he ever admitted to using your photos without your consent, you have him my the do dahs!!
Copyright is theft and I know from experience that the courts are on our (the photographers) side in these matters, clearly it is up to you if you choose to go down the legal route, usually just the threat of legal action is enough for those in the wrong to sort themselfs out.
Trev