A330
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 33000
Situational Awareness; Communication Breakdown
Ground Event / Encounter Aircraft; Ground Incursion Runway
General None Reported / Taken
Human Factors
Holding short of Runway 27R at A3. Both Captain and FO (First Officer) were new to the airport.  We received a clearance that we understood as lineup and wait behind a departing heavy jet.  The [Relief Pilot] who was very familiar with the airport said stop.  We stopped but the nose of the aircraft had crossed the hold short line.  We immediately notified Tower.  The red light bar was not illuminated.
I believe we were holding short of A3; short of Runway 27R LHR; awaiting our turn to take the runway for takeoff.  Other aircraft were short of A2 and A1 so our sequence for takeoff was unknown.  We were already stopped; sitting still with the brakes set.  It appeared that we might be next for takeoff.  Tower called us and gave the instruction to hold position. The FO (First Officer) acknowledged and read back the instruction.  A few moments after that call the [Captain] released the brakes and added some thrust.  I wrongly assumed he was positioning the aircraft a few feet ahead to get closer to the hold line.  From my seat as the [Relief Pilot] I could not see a hold line or any red light.  Then I noticed him add additional power and that's when I realized he was thinking something entirely different; like take position on the runway.  I immediately verbalized no no no and grabbed at his arm.  The FO also verbalized no.  We immediately stopped but had moved about 50 feet; across the hold line.  Again; I still couldn't see it from my seat.  The FO called the Tower to report that we had crossed the line.  They sent a B747 around.
Flight Crew reported Captain passed the hold short line causing landing aircraft to go-around.