A contract has to have 'consideration' (an exchange of value) to be legally binding in the UK. HSBC are taking this bank for free, but since you can't do that they say £1.
An even funnier term comes out of free property leases. Due to some historical convention the consideration is sometimes still written as 'one peppercorn if demanded'!
The peppercorns are still taped to the folder of company documents in my filing cabinet
> as aforesaid for a term of Nine hundred and ninety nine years from the date hereof subject nevertheless to the proviso for re-entry hereinafter contained YIELDING AND PAYING THEREFOR [sic] during the said term a yearly rent of one peppercorn (if demanded) to be paid on the First day of January every year
Possibly the most impenetrable sentence I've ever read, and I had to look up the whole peppercorn thing. Nobody's ever requested anything so am yet to post any peppercorns.