Originally Posted by
serfty
T4 security and South T3 pier security are one and the same.
The 650 metres includes a possible walk between the end of the Northern T3 Pier to either the end of the Southern T3 Pier or the most likely T4 gates.
I've clarified my post somewhat.
As of March going from T3 (whether north or south) to T4 requires a reclear of security (which is just outside the Virgin lounge). The gates that Virgin uses in T4 or right at the beginning of the T4 pier.
The walk isn't long (like JFK T4) and 35 minutes is more than enough time although Virgin is usually quite strict with the door closing 10 minutes before departure.