Complex sentence: Andrew Weston and Chris Williamson had worked together at Leicester Polytechnic School of Architecture along with Steve Humphreys who joined the practice when Weston Williamson became a limited company in 1991.
Split into simpler sentences: Andrew Weston and Chris Williamson worked together at Leicester Polytechnic School of Architecture. It was at Leicester they also met Steve Humphreys, who joined the practice when Weston Williamson became a limited company in 1991.