[PoachedSausage]

What do Ofcom do to enforce it?

They used to have a number of spectrum monitoring stations, however they were decommissioned, I know someone that bought bits of it at auction.

[g_p]

I believe any enforcement Ofcom do these days is reactive, and in response to reports from licensed operators.

A lot of the new "shared" access licenses do not give guarantees of interference protection though, so I imagine Ofcom enforcement would be on a best-effort basis there.