I don't feel that you answer properly addresses the scenario that I am presenting.
Example:
The UK is in possession of territories that total 38 PPs, to include the original 19 PPs production center territories.
They are hit by u-boats in the convoys to the tune of 17 PPs on the Axis turn, which lowers them to 21 PPs on the Income Track.
They receive 10 PPs from the US via Lend Lease bringing them back up 31, but they choose to only spend 20 PPs on their turn, saving 11 PPs.
At the end of their turn, the UK once again pulls 38 PPs, giving them a grand total of 49 PPs on the Income Track.
My point in asking this question is the idea that the saved 11 PPs should not be affected by the next turns' Axis u-boats attacks. The Axis convoy attacks should only affect the UK for a maximum of 19 PPs (38 - 19 = 19). Now the extra 11 PPs (along with the 19 PPs from the production centers) can still be reduced, but only through strategic bombing and rocket attacks.
Craig