Digging the thread, thought I’d give info since this thread appears on Google search results a lot.
FasterPayments transfers are only instantaneous among “Direct Participants,” aka the high-street banks and a select few. Challenger banks and financial institutions have to partner with and route their transfers through some of these Direct Participants and hence that adds additional delay.
Core members aren’t really keen on onboarding challengers as I guess they can charge them to route transfers through them. Similar to the BGP peering market for the few computer guys out there
Please also note that even among Direct Participants, transfers above 10k and the occasional random transfer under 10k can take a bit of time.
FasterPayments only guarantees two hours within working hours and one business day otherwise.