I think that you need to increase the medication, Carandrog!
;-)
If I recall correctly (which, at my age and state on inebriation is probably quite unlikely) an uncrossed cheque, payable to 'Alf Bloggs' could (at the bank's discretion) be paid into the account of someone else if Mr Bloggs had signed on the back of it.
The only signature that should appear on an English banknote is that of the Governor of the Bank of England. Anyone else signing it (or writing on it in any way whatsoever) would be committing a criminal offence.