4505 on service 7, other two aren't allocated today.

Edit: 4508 is on 9/27A as changeover for 1915, 4509 spare in Middlesbrough

Edit2: 4509 replaced 4069 on 17B at 1120

Edit3: 4069 has gone back on the 17B board at 1320

Edit4: 4509 replaced 1494 on 9/27A at some point in the afternoon
Also, 1739 on X3/X3A