Nope, I don't accept that the recession has that much to do with it - in 1983, we'd had the best part of four years of a severe recession, and the route was still booming, so much so that the fifth rotation 335/6 was added in 1984.
The route took a major hit circa 1977 with the introduction of accelerated train services on the East Coast Main Line, but I'm unconvinced that they've improved that much in recent times.
Mess around with times and equipment,and folks go elsewhere. There was even loyalty through severe punctuality problems through the late 'eighties.
Having typed my last post, I drove down the A66 through the 23 centreline at around 1630 today, to see a Barbie Jet on finals (almost as a symbol!). I've no idea of the timetable these days, but northbound at that time is not the optimum. The old 338 at 1725 was bang on, and used to run pretty much ful, as it fitted in well with the end of the business day.
Oh, and the Tony Blair factor. Indeed. When John Major was PM, Huntingdon magically got it's own non-stopper to Kings Cross, which disappeared soon after the General Election of 1997...