They could also speed up their response to incidents, meaning that delays aren't so lengthy. To try and write this off as outside the control of the industry is disingenuous.
We've had this argument before (in respect of bridge strikes last time). Yes, you can make *anything* within the control of the railway (duplicates of all signalling, hot spare stock standing by at every station, two staff members for every job to cover sickness, etc.) But at the end of the day, birds fly where birds fly and, short of culling every pheasant in the UK, at some point a train and bird are going to try and occupy the same point in spacetime.
And there's nothing the railway can do to prevent it.
Unless the incident happened fairly close to where the fitters come from, over an hour seems quite reasonable for a fix. Let's assume that 'outside Swindon' means a 20 minute drive for the fitter, the timeline likely goes something like this:
T+0m: The train loses air. Driver tries to get air back again.
T+15m: Having tried several things, including walking the length of the train to see if there's a loose hose, driver calls for a fitter
T+20m: Control gets hold of the fitter, (s)he gets the necessary bits and bobs and hits the road.
T+45m: Fitter is on site, gets to work.
T+60m: Work finished
T+65m: Train has air, is capable of movement, signaller advised
T+70: Route set, train away
So that's over an hour in best-case scenario. Throw in rush-hour traffic, a stubborn hose connector or an inaccessible location and it could be double that easily.