Complex sentence: The machines have been in use in the UK and Europe since the early 1990's and tend to be crewed by Scotsmen, due to the fact that the company who makes them (Loram Maintenance of Way) had sited their first European office in Glasgow.
Split into simpler sentences: The machines have been in use in the UK and Europe since the early 1990s. The company who makes them, Loram Maintenance of Way sited their first European office in Glasgow.