Because the type had a relatively short life in London, the class was never extensively overhauled or repanelled unlike the standard RT class, many of which survived in London service until the 1970s.
Stripping of RTW335 has revealed that the type employed the standard Leyland "patented metal construction" with a basic steel frame with timber inserts. But stripping has also revealed that all the timber is essentially rotten, whilst much of the high quality steel used is still in good condition - although there are areas of corrosion - particularly around the rear platform and cab area.