You are talking prototypes - these were a different to pre production and production 101s - they looked different and proved the original idea for the 101 did not work and as a result everything was resigned from suspension, drive, engines and body. It was about this stage that the powered trailer idea was disgarded though an early pre production 101 did have it fitted with the same result as the prototypes, that is why no production 101s had the trailer.
The 101 was already in service with the UK before we did trials on the 101 here.
Garry