Flying a week on Thursday with QR. Will I be OK buying a duty free bottle in LGW and get it through to BKK via DOH in hand luggage OK?

I have seen problems before with people buying bottles in CAI and having them taken off them in transit through LHR. The "if you bought it in the duty free and its in a sealed bag" rule apparently only applied if you bought it in an EU airport and not cairo.

Just dont want to have the same problem transiting Doha. LGW do a nice 2 litres of Morgans Spice rum for £15!