I've just remembered I had a fretless bass (conversion). It was a Wilson Mercury 4, that had belonged to my first ever band's bass player before he bought a decent Aria. Ugly looking thing with a very
thin neck. Very woolly sounding. Short scale as well. Wal style headstock IIRC (but was made before Wal existed).
This is the only picture I could find of one. Mine was just a natural mahogany finish.
The frets were pretty worn so I tried replacing the frets myself, which didn't go well. So a mate took it to have a go and when it came back he'd given up on fretting it, ripped all the frets out, filled the slots and put epoxy rather unevenly all over the board. (Sam Spoons will probably recognise the name Jim Champ from various FB sailing groups). It had also somehow been fitted with two sets of Mighty Mite P-bass pickups, but due to the very thin neck/small string spacing, these severely crossed over and the two middle strings were sensed by about 4 poles each!
It sounded awful and played badly, so it generally just got put to one side and forgotten about. String to string volume all over the place. Eventually it got binned.
I will get a fretless bass one day, as I too was rather taken with the Percy Jones Wal bass sound.