Hi I am a pub manager, and after doing my books today £260 is missing, can I deduct this from staff wages as someone has obviously stolen it?

No.

I'm curious to know what your reasoning is for this. Every employee is responsible for the actions of one? Never mind that fact that it might have been stolen by a customer reaching into the drawer. People work in pairs, one distracts you on one side of the register while the other one steals. Or that fact that you are one of the employees... how will you feel if the owner holds you liable?

If you have proof, beyond a doubt, which staff member stole it, you may call the police and press charges,

But first no, all you know is that the books don't balance, you are, not sure why or how

And don't know if one did it,

So no, of course you can not just take it from all of them.

Why don't you just take it out of your wages? After all, that's what you would be doing to the innocent party/parties.