It's very likely that those vans were used in the 1970s to capture the RF leakage from the local oscillator and other driving circuitry of the CRT TVs. But whil

It's very likely that those vans were used in the 1970s to capture the RF leakage from the local oscillator and other driving circuitry of the CRT TVs. But while it's still technically possible to detect RF leakage from modern LCD TVs, I'm not sure BBC has the capabilities to deploy those and achieve reliable detection. Many people would say these vans became hoaxes at some point in history.