They did in 1984, think NUM strikers from oop north trying to join their brothers in Kent.....
Think 'Kettling' of City of London Bankers caught in the maelstrom of Anti capitalist demo's in London in recent years....
Now, as to whether the 'bobby on the beat' actually joined up to use/abuse (delete as appropriate) this restriction on 'personal freedom' is open to debate, perhaps the orders come from VERY high up in the chain of command...