Communication Breakdown; Distraction
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Took Evasive Action
Aircraft; Procedure; Human Factors; Environment - Non Weather Related
While on final approach to runway 27L at EGLL; ATC assigned us a speed of 160 knots until reaching a distance of 4nm from the runway. Unfortunately; I didn't hear the speed assignment. I started to slow prior to reaching the 4 nm point. Prior to turning on final; we had an auto throttle failure. The failure happened during the descent on base leg. We made two attempts to re-engage the auto throttles but we were unable to recover the system. When we turned and intercepted the localizer and were cleared for the approach; it was obvious we were gaining on the heavy traffic in front of us. We were 3.5 nm behind the heavy and picking up wake turbulence. I speculate this is when we were given the speed restriction. While clearing the runway; ATC asked why we started to slow to our final approach speed early. We told the tower we started slowing because we were picking up turbulence from the heavy aircraft in from of us.  I believe I missed the speed restriction because of three distractions in the cockpit. Auto throttle failure; wake turbulence and a loss of separation behind the heavy aircraft. When I heard the approach clearance; I assumed responsibility for wake turbulence separation. I was aware of the [policy] pertaining to expected speed restrictions on final. When I saw the loss of separation; we should have queried ATC about any speed restrictions.
B767 reported encountering wake turbulence in trail of a heavy jet on approach to EGLL. Reporter stated he missed a speed restriction because of distractions; and wanted to slow because of the wake turbulence.