Travellers who pitched up at Queensway car park have been ordered to leave by 6pm today (Friday), it is understood.
Police visited the illegal encampment, which consists of 17 caravans, on Wednesday morning (June 26).
And officers have been working alongside Dacorum Borough Council to "resolve" the situation.
A council spokesman said: "The police have been working with the travellers and all occupants are expected to have moved by 6pm."
More to follow.