From Law wiki, the wiki for law research

[1845] 7 QB 742. The claimant was arrested after punching a policeman who tried to obstruct his passage along Hammersmith Bridge. Part of the bridge had been (unlawfully) closed to pedestrians. His action in False imprisonment failed, because the court held (by a majority) that obstruction of passage was not a sufficient deprivation of liberty to cosntitute an imprisonment.