These internal user wagons,  Nos. 20 and 35 worked for Castle Cement at their Pitstone works, and kindly donated to QRS by them in 1991.  These wagons were once owned by Tunnel Portland Cement, of West Thurrock, who opened the Pitstone workings in 1937. 

No. 35 was built by Bolton Railway and Ironworks Co. Ltd., now Weston Engineering of Bolton, in 1957.  It has two numbers "10" and "56" possibly a date, stamped onto two of its spring hangers.  This wagon also carries the only surviving builders plate.  The buffer springs of No. 35 are alternate discs of metal and rubber, whilst those on No. 20 are heavy coil springs.  An interesting asymmetric feature of both cars is the strengthening plate on one side and the absence of the brake handle on the same side.

Possibly this, with the curious extensions on the upper end of the bodies, is associated with the tipping machinery that was installed at Thurrock after the Second World War.  It is also unusual to see oil axle boxes on a wagon that was designed to be tipped.  There was a change from woodern side tippers to metal wagons at the same time.  That the brake handles have been cut off rather than simply not fitted, suggests that the re-bodying of existing chassis.

With disc wheels and oil boxes, No. 20 seems to be of unusually good quality for internal use.

Reference: Ray Jackson - Quainton News No. 92 - October 2004