BYOB
It is not only LHR that has been running low on De-icing fluid. AMS, FRA, CGN, DUS, NUE, etc. have all recently had moments when they wish they had greater stocks. This winter has been particularly bad and maybe handling companies may wish to wish to hold greater stocks in the future. But there are other airports (LGAV?) where some well known operators have also had to take own their fluid to rescue their aircraft. And have you ever tried to de-ice in LFMN?
PM