ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
General None Reported / Taken
Environment - Non Weather Related; Procedure
[We were] given takeoff clearance approximately 30/35 seconds after a heavy B747.  [We] delayed takeoff for approximately 30 more seconds. Wind report was 280/7. Rough ride after takeoff 300 FT to 1;300 FT. [We] reported event to EGLL Tower. I thought EGLL provided a 1 minute minimum delay interval between heavy aircraft. They didn't. [They] should consider longer delays when winds are calm or straight down the runway.
B777-200 pilot reported encountering wake turbulence after takeoff from EGLL in trail of a B747. Pilot commented he felt separation standards were not followed by ATC.