Brymon was the first, they did all the hard work including the first landing at Canary Wharf early eighties with the dash 7. Capt Harry Gee in command.
All true, but DHC did the early heavy lifting with the revolutionary Dash 7.
1) Convinced the ARB/CAA to recognise that there was technical and commercial justification for STOL aircraft to be certificated to different standards than the usual FAR 25 Transport Category (i.e. 7.5 degree approach slope (although this was later reduced to 5.5 degrees to allow other, less capable types in).
2) Considerable lobbying and marketing in support of the LCY concept, which gave London Docklands the courage to proceed with the airport against much resistance.
3) Bought Brymon and supported it financially for three years after its collapse when the pound went south in 1983.