I know it's the longer barrelPhoto TP with breech open to determine whether 25 or 26 mm piston bore.
The longer barrel 77 with 25 mm internals would be desirable. Not so much the 77K.
"Immaculate" and "stored in loft", do not readily combine.
£200 to £250 would be reasonable if purchased without close inspection of internals.
If opened up, expect a four leg steel spring guide, no top hat and end of spring resembling a cork screw.






