Reg question. Mixing flex (2.5 mm² CPC) and T&E (1.5mm CPC). Same MCB. OK under BS 7671?

Can't find a definite answer from the regs. I know it's electrically fine. I’m wiring a small garage CU and have a 16 A B-type breaker feeding a socket radial.

First leg of the circuit uses 2.5 mm² 3-core flexible cable (3183Y), so L/N/E are all 2.5 mm². All terminated with ferrules at the CU.

I just want to add a second leg from the same B16 breaker, but using standard 2.5 mm² twin-and-earth (so CPC would be 1.5 mm²). Because I've already got some T&E.

Do you guys know if it's fine under BS 7671? Cheers!