Well it is what it is …… the rear of an MGB that has been converted into a trailer! Up for auction this weekend the 18th.

No brakes, so you’ll have to keep your gross weight down below 750kg, but you’re hardly going to use it to move brick rubble.
More info at …… https://mathewsons.co.uk/auctions/auction-dates/vehicles/14635-mgb-trailer