None of these vehicles where wholly conventional in their design and this presented a challenge to the salesman. Managers and engineer buying vehicles tended to be conservative and not only did they have to be convinced that "this was the better way to do it" but also that it was worth paying more money for the Sentinel products. It became clear that the best way to convince buyers was to demonstrate the appropriate vehicle in the buyer's own works carrying out the actual duties required. This became the general sales strategy for many years, and involved moving locomotives from site to site in the United Kingdom. The locomotives travelled on British Railways and under their own power where possible. The demonstrations created considerable interest, two locomotives, one 100 hp and one 200 hp were continuously employed moving from one site to another, particularly within the National Coal Board and Steel Works.