Trident G-ARPC operated the first Glasgow flight on 12 January 1975, Edinburgh was next on 1 April 1976 followed by Belfast on 1 April 1977, not sure about Manchester. The Super Shuttle concept was rolled out all routes on 30 August 1983 in response to the BMA challenge on these routes. BMA had applied to operate Heathrow to Glasgow and Edinburgh in 1981 but were turned down. They won on appeal and their services started on 7 March 1983 and extended to Belfast later. By the end of 1983 BMA had a 28% share of the market. BA launched an advertising campaign in 1983 showing a single passenger being flown in comfort on the back up aircraft. In order not to fall foul of the advertising standards authority BA had to demonstrate that this had actually happened and it had – once. However there were many times when only a handful of passengers were flown on back-up aircraft (cost of a single ticket in 1983 was £56 – cost of a 1983 Trident flight to Heathrow from Glasgow - £10,000). When BA and BMA reached an agreement on overflow passengers, BA passengers were passed to BMA with a £5.50 voucher being the difference in the cost of the tickets. On the Edinburgh route BMA were operating 5 flights a day to BA’s 11. As already stated Concorde was occasionally used on the routes for publicity eg a flight on St Andrews Day on the Scottish routes.
It did all seem to fizzle out although there must have been some definite cut off point.