For some reason, despite not having worked in the UK for well over 20 years, and not having entered it on a form for a decade more, I still remember by National Insurance number.

This came in handy a few months ago when I became eligible to vote from abroad again, and this was one of the things they wanted to know, to 'prove' I was who I said I was.

At some point I have to go through the process of getting my years of state pension contributions in the UK transferred to Spain. That will involve a few brick walls, I suspect.