Weird. I wonder how Bittylicious operates safely as they're a UK exchange and make their transactions via Faster Payments through any UK bank accounts (and even some European ones I believe) though the money goes straight from buyer to seller and not passed to/through Bitty.
That's exactly how - payments are made directly to Bittylicious sellers and thus Bittylicious doesn't have to rely on any UK bank accounts.
It's also easier because customer money isn't really held by anyone - these are simple "I buy, you send" type purchases rather than deposits.