My initial reaction is as per most above – tell him to pack up and f off. However, a hell of a lot easier to hand him £67.50 and then tell him to pack up and f-off. And get him to sign some kind of receipt acknowledging receipt of the money and terminating his rights of occupation.
If it only costs £67.50 to solve this problem, then I wouldn’t bother with a solicitor as £67.50 won’t even get one to answer the phone. And you’ve already effectively written off the previous sums owed.
Hand him the dosh in return for something in writing and make sure he vacates on Sunday.
If it comes to a legal argument later, you can demonstrate that you have acted reasonably at every stage.
PS speaking as a surveyor with a large portfolio of residential tenants.