The aircraft was departing from Runway 27L on a scheduled passenger flight to Kuala Lumpur. The flight crew consisted of an operating captain (the commander) and a first officer who was experienced as a ‘cruise pilot’ on the type but was relatively inexperienced as a handling pilot for take off and landing on line operations. A second captain and first officer were occupying the supernumerary seats on the flight deck. Normal pre-flight procedures were carried out and, as the first officer was to be the handling pilot, the commander gave him a take-off briefing which paid special attention to the correct rotation technique and transition to the initial climb. For noise abatement reasons full take-off thrust was to be used and the aircraft flown at a speed of about V2 +10 kt until passing the flap retraction altitude. This technique was used to minimise noise in the vicinity of the Noise Monitoring Terminals (NMT) located close to the Standard Instrument Departure routes around the airport. The requirement is that the aircraft should pass the NMT at not less than 1,000 feet above aerodrome level, then should maintain a climb gradient of at least 4% (243 feet/nm) until passing an altitude of 4,000 feet. The Tower controller passed the surface wind as 210øM at 15 kt as take-off clearance was issued. The take off commenced at 0957 hrs. During the take-off acceleration, the commander noted that the airspeed indication (speed tape and trend vector arrow displays on the Electronic Attitude Director Indicator) was fluctuating at around 100 kt and at V1 . The rotation was commenced at V R, but the commander perceived that the speed increased towards V2 +20 kt as the rotation continued. In order to assist the first officer in achieving the correct speed for the initial climb, the commander made an additional rearward control column input. This caused the aircraft to pitch up at an increased rate and the tail of the aircraft struck the runway as the aircraft left the ground. This was felt in the rear cabin and two of the four occupants on the flight deck were also aware of the contact with the runway. The stick shaker activated momentarily and a forward control column input was made to reduce the pitch attitude. The aircraft continued to climb away, with the first officer adjusting the pitch attitude to the correct climb attitude. The landing gear was not retracted until the flight path had stabilised and the aircraft was passing about 1,000 feet agl. ATC informed the aircraft that some debris had been observed falling from the tail section. The aircraft climbed to FL100 under radar control and was geographically positioned in an area so that it could dump fuel. The aircraft dumped 74,000 kg of fuel then returned to London Heathrow for an uneventful landing on Runway 27R at 1057 hrs with the commander as handling pilot. The actual landing weight was 283,400 kg, which was some 2,300 kg below the maximum landing weight limit. It was determined that the presence of rain shower activity in the vicinity of the airport at the take-off time could have produced transient wind shear effects and local wind gusts.