I suppose I get no credit for UK taxes paid over and above what I paid Uncle Sam?.
The tax situation, for both you and your wife, has become much more difficult simply because you’re a US citizen receiving US and UK pensions whilst a resident in the UK. I’m sure you’ve figured this out already. In your circumstances the first year of US and UK filing are the most complicated, but once you’ve been in the system for several years, it should ease a bit. As a general rule (in my humble opinion), always pay HMRC foremost once you’re certain of your tax status and the status of your pensions. On the US side, be sure to check your liability to New York State (under domicile rules), if any, even though you’re now living in the UK.
For the US, your pension income is unearned. (You cannot use Form 2555.) You can offset any taxes paid to the UK (HMRC) by using Form 1116 (Foreign Tax Credit). Not an easy form to follow, but certainly not insurmountable. Generally, once you claim the foreign tax credits from Form 1116 back on to Form 1040, you should not owe any US taxes (due to the higher tax rates in the UK).
Under the US/UK Tax Treaty, your US Social Security can be claimed as only taxable in the UK. It’s my understanding that to invoke the treaty you should file Form 8833. Invoking the treaty can become tricky. You certainly may want to seek professional advice if you chose this route.
As a reminder, be sure to file an FBAR to the US Treasury (which is separate to your US taxes) if you are so required.