For 30 minutes on day nine of the Jane Longhurst murder trial yesterday all attention turned to the question of the stretching properties of women's tights.

Chartered textile technologist Julian Ellis, an expert in the elastic properties of tights, appeared as a witness for the defence to explain his theory about the severe indentations discovered on the strangled teacher's neck.

The court had already heard the pair of tights Coutts is alleged to have used to strangle Jane were pulled so tight the pathologist who examined her body found it difficult to get scissors underneath.

In the opinion of Mr Ellis, however, the elasticity of nylon tights meant it was possible they had tightened further, of their own accord, after Jane's death.

While they would have had to be tied relatively tight to stay in place in the first instance, further indentation was likely to have occurred after death, argued Mr Ellis.

Revealing the results of experiments he had carried out on himself recently using nylon tights, the expert said he had tightened a pair round his thigh, just tight enough to hold, and found it left "quite an indentation".

At the end of the day, he said, nylon round the top of popsocks left an indentation; even underwear could leave an indentation.

If stretched, nylon wanted to go back to its natural state, said Mr Ellis. If something was stopping it, pressure would be exerted on that object.

He said:"The nylon is just like a rubber band. If you had a rubber band round your wrist, the tension would remain."