recovering luggage left on holiday - customs forms

[QuattroDave]

Evening good people of PH.

My family and I had a lovely two weeks in Mexico, returning home yesterday morning.

To bring things home with a bump before we even left the country, as we were checking in our daughter realised she's left her carry on backpack in the private transfer car, which had long since departed the airport. Once tantrum was over, we'd gotten through secuirty and calmed the child down I set about getting in touch with the hotel.

First the good news, the hotel were quickly able to find the backpack in one of their cars and have inventory checked, logged and secured the backpack.

For context the backpack contains only low value personal items of a child (prescription glasses, blanket, cuddly toys and prescription medication - which I've asked the hotel to dispose of as couriers don't allow the transfer of medication).

Today I have arranged for UPS to collect the backpack later this week. When completing the purchase I was informed that I had to fill in a TOR1 form. Reading the form it's for the permanent change of residence to the UK which is not the right form. HMRC guidance pointed me then to the C1314 form which again doesn't seem to be the right form as it also requires the C88 form.

So my question to the learned people of pistonheads is, does anyone know what form (if any) I need to complete to prevent further delays and pain when it's collected this Thursday?

I've also asked the question to the courier company also who will hopefully respond before the collection date!

Thanks in advance.