Beard actually grabs Joan's arm. Sure, Ted, go up to an unmarked windowless van in the middle of London. The problem exactly with Ted trusting easy. Even if his insight usually saved him from getting involved with bad people, clearly it didn't help this time.

"Alright so... How do we follow this?"

There's no way to see the registration. And they probably don't have access to CCTV and all that without the cops. But Ted's phone wasn't in the alley, so it probably went with the van for at least a while.