I just found this coin in the archives of a Polish auction house. It sold for EUR 103 in 2018.
What's more interesting than the coin itself is the old collector's ticket it came with.
It previously sold for £3 in 1966, then prior to that for the princely sum of 7 shillings and sixpence in 1950 !
An online calculator says the inflation adjusted value of £1 in 1950 would be £35 today, so that 7/6d would be equivalent to £13.18 = $17.80 today.
I remember when I was a kid in the 1960's you could buy a small chocolate bar from the railway station vending machine for 2d (two shiny pennies).