have days stuck downroute which would have been days off at base, become days off achieved thus straight back to work upon return to LHR/LGW.
Yes. However that is something I will be discussing with my manager as, I believe, under the rules we can claim either an extension to our leave or an additional day/days to a Duty Free Week. It just won't get processed automatically and your roster will be moved forward as normal. Like expense claims you will need to be a little proactive in claiming disruption back.