Back to the original topic for a minute...
The basic principle of international debt is that a nation capable of repaying debt should do it, unless the debt is so large that it can never be repaid or does not have the resources to develop a GDP capable of any repayment. If repayment contributes to extraordinary political and social instability causing further social and monetary costs, buy backs, rescheduling, swaps or forgiveness are considered.
Since Great Britain was/is a significant creditor as part of the London Club (a group of post WWII private international debt holders) it would have been self-defeating to ask for, or have debt relief for such a small amount when owed many times that from other nations. Repayment was continued and made neither as a display of British national pride, nor US unreasonableness. It was to uphold the basic principles and mechanism of international debt.
It would look foolish to ask for payment of debts owed to the England by poor countries with little resources or ability to repay if England was given, or asked for debt relief.