Yeah a long long time, Dimbleby reported outside Downing street in 74, i believe the last time this kind of situation arose.

Brown is also notorious for this sort of thing, when he was in the shadow cabinet he had sources in the civil service and would leak stuff a lot, however when one of the Tories were doing it, the police got called and were actually allowed to enter the commons by the speaker. This caused a fuss cause speakers in the past have refused Kings entry at great personal cost, to preserve the parliment. This was all done without a warrant to search, and they impounded computers which would have informartion from constituents.