Police have arrested a fourth person in Sussex over an attack on the boss of a pharmaceutical testing firm.

Yesterday we reported how three men were arrested over the assault on Brian Cass, head of Cambridgeshire-based Huntingdon Life Sciences.

One was arrested in a raid on TV writer Carla Lane's animal sanctuary in Horsted Keynes and two more in Hastings.

Cambridgeshire police have now revealed that a fourth person, a 29-year-old woman, was arrested in Hastings.

Along with the others, she has been taken to a police station in Cambridgeshire for questioning.

Police said the four were being questioned in connection with the attack on Mr Cass, on suspicion of causing actual bodily harm to a man who went to Mr Cass's aid, and over suspected possession of a prohibited firearm.

Cambridgeshire-based Huntingdon Life Sciences has been the focus of a series of protests because of its use of animals for drug testing.

Mr Cass, who is in his early 50s, was attacked as he arrived at his home in St Ives on February 22. He suffered head injuries.