Originally Posted by BAAZ
Unless they check your BP on the airside buses you should be OK. And IIRC there was someone on here who had parked his car at T4, landed at T1 and used the FCC and airside transfer bus to save the schlep to and from the HEX, successfully and without an onward BP.
They don't check BPs on the buses.
I can confirm that you can happily use the transfer buses like this. I have done it before going from T4 to T3. Was intending to go through FCC, but the queue was so horrendous when I arrived in T3 I went landside and then went through the main security. I did not have a BP as transferring to VS and picked one up from the main check-in desks.