@James *****
your friend has two options
BUY a single entry tourist visa from the thai consulate in London online before he wings his way here and when he enters he'll get stamped in for 60 days
OR
Come in on a 30 day visa exempt entry and then apply for a 30 day extension at the immigration office for 1900baht
DO NOT OVERSTAY..
We're done, thanx one and all for the advice (y)