Jonathan – just confirm:
1. you are a UK citizen resident in Spain
2. You need a second passport for additional visa’s etc
3. You are not returning to the UK for some time
4. You would like your “additional passport” pdq.
Please conform that this is indeed correct and I will happily put my skis on go to my local post office and ask the question and hopefully ID the online form you need. I will also get my travel department to phone the passport office to check. You shouldnt feel as if you have to lie, becasue this is not a unique problem.
Look forward to hearing from you