"aircraft" seat up for auction. Identity ?

Hello,

I found this whilst wandering around the internet.

https://www.the-saleroom.com/en-gb/auction-catalogues/wotton-auction-rooms/catalogue-id-srwot10102/lot-dcd07ec6-00e4-4adc-bc85-a87200d19f49
It would appear to be from an aircraft but I’ve looked at all the usual suspects and can’t identify what it’s from. All the plaques are in English. I looked up WM105 on UK serials but the WMs don’t appear to start until WM149.

Over to the forum aviation sleuths then on this one.