You do need to declare that. You are required to list all income from any source no matter how big or small.
The easiest wat to declare this income is to scroll all the way down in the wages and income section to the very bottom and click on 'Miscellaneous Income' and then 'Other Reportable Income'.
That gives you a space to enter a description and the amount that you received.
If you were taxed on your UK pension then you can enter any taxes paid as a deduction in the deductions and credits section by going to 'Estimates and Other Taxes Paid' and clicking on 'Foreign Taxes'.
@davidrogerbrummitt
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