Can't help with what police station as lawyer handled it all but just had a look at the copy I took of our POA and that specifically mentions the passports. Having included both our passport numbers it goes on to say:
"The appearers show me and I give back the passports referred to. I certify that I have identified the appearers by their passports and they declare that they intervene in their own name and right ................................"
As the UK Notary signs the POA then by virtue that the passports are covered this should suffice. If not your lawyer clearly needs to explain why .
Hope this helps.