Ripsnort, Curval -
Neither of you are right.
In 1939 the Neutrality act allowed American aid to be sold to Britain providing it was paid for, in full, up front and in cash.
By 1941 Britain had been fighting Germany for 2 years, alone and unaided; virtually bankrupt, there was no money left to buy arms or supplies (even ownership of American based companies had been sold off) and the Lend-Lease Act was passed. This allowed credit to be given for arms - which was totalled £27,000,000,000 by 1945.
The transfer of ownership of military bases was part of this second agreement.
Lend-Lease wasn't a freebie. It was the exchange, sell, lending of material. I also believe the UK is still making interest payments on the debt, although I can't seem to find information regarding the extent of debt remaining.