Bagso, British Midland dropping Liverpool - Heathrow was to enable them to start Heathrow - Brussels at a time they were struggling to secure additional slots. Teesside and Leeds lost their links for similar reasons. KLM carried something like 150k passengers in its last full year of operation on Liverpool - Amsterdam and the decision to suspend the route was taken at the height of the economic crisis. Demand, or lack of it was therefore not the prime reason in either case.
Much has changed since the days of BMA, not least the Liverpool economy, and why you should be so concerned that some of the City's businesses feel connectivity to Heathrow is important for the on going development of the City's economy puzzles me.