Priestley is considered to be one of the most promising members of Cowan's group that trains alongside Ohuruogu, the Olympic 400 metres champion, and Simeon Williamson, Britain's most promising young 100m sprinter, at the Lee Valley High Performance Centre.

Priestley, the British Indoor 60 metres hurdles champion, has tested positive for clenbuterol, a stimulant used in asthma treatment, it was announced yesterday.

He is the first British athlete to test positive since Dwain Chambers in 2003.

Cowan told the Mail on Sunday: "It is devastating.

"I am led to believe it may be to do with some contaminated product but I have no idea.

"I wasn't there, I don't know what took place and I am just trying to get through the day."

Priestley is now facing a two-year suspension and a lifetime ban from the Olympics under the rules of the British Olympic Association (BOA).

Ohuruogu faced a similar ban after being banned for a year in 2006 following a series of missed out-of-competition tests.

But she successfully appealed to the BOA and went onto lift the Olympic title in Beijing in 2008.

Cowan said: "You don't want to be associated with these sort of things and I've got to think that innocence helps the kid.

"People say, 'You must know everything' but you can't know everything with 15 athletes.

"It's a shock.

"It's hard and, from a coach's point of view, it is stressful.

"I have just got to wait for the next two weeks and see what happens.

"I think that most of his supplements have gone off to be checked.

"Callum is just stepping on to the pathway to be an athlete and he had showed immense potential.

"I am worried about him.

"I tried to call him but he is not picking up.

"There are things that the authorities need to go and find out so I'm going to keep my fingers crossed for him and his family.

"I've just got to keep praying for the boy that things can turn around."


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