Client asks if a golf club membership is tax deductible

His argument - he's joining the golf club so that he can meet prospects and hold meetings with prospects/clients at there.

My initial reaction is that this one goes in the box marked 'pushing things a bit too far' and it is not deductible.  However maybe there is an argument that part of the reason for the membership is for business development so there is a proportion that could be argued as a business expense - admittedly only a small proportion.

This is a new one for me - any thoughts on this?

Thanks in advance