She walked to the escalator, descended to the ground floor and left the Centre. She looked across the large open car park towards the High Court building some six hundred yards away. There, the man who had killed her son was on trial. The man they said had killed her son. Since the trial had started, Annie had deliberately avoided newspapers, televisions and radios. She had certainly not ventured anywhere near the court. Now it was time to find out what was going on – for herself.

Everyone is afraid of something: open spaces, heights, spiders, living, dying, the VAT man. Nothing chills the blood of the defence lawyer more than the spectre of the apparently genuine independent eye-witness. The public should adhere to the three golden rules for witnesses to a crime: do not get involved by telling the police; if you must tell the police, do not give your name and address; if you must give your name and address, do not give your real name and address.

Barclay Thomson had chosen to ignore each of these rules in turn, in a big way, and now found himself opening the batting on the seventh day of the trial.

Thirty-something, he gave all the outward appearance of being a product of the sixties. Long straggly hair, thin, droopy Zapata moustache, combat jacket, jeans and a T-shirt bearing a picture of Che Guevara – he looked as if he was about to audition for the lead role in a remake of Citizen Smith.

‘Power to the people!’, muttered Anderson.

‘It may be my elbow which needs the power,’ came his senior’s surly response.

He deponed that he was a musician, a drummer, with a Glasgow rock band which rejoiced in the name of the Culture Vultures.

‘The who?,’ inquired the Advocate Depute.

The reply, ‘No, the Culture Vultures’, caused much mirth amongst the jurors, especially as it sailed above the heads of both counsel and judge.

His manner of speech disclosed he was not uneducated as he confirmed when questioned on the subject. He parents were professional people and he had attended Glasgow Academy before graduating from the London School of Economics with a BA degree in Politics and Economics. The Depute was setting this man up as a sane, sensible witness, despite his singular appearance. Instinctively, the jury knew something was about to happen.

After describing where he lived and confirming that from his lounge window he had had a clear view of the BMW, he was asked about the critical matters.

‘I write songs and I was working at my keyboard. I had been at it all night but nothing was happening for me. The room was smoky and I went to the window to get a breath of fresh air, and it all just happened. Like, man, I thought to begin with it must be the telly, making something like Taggart. It looked seriously real.’

‘What did you see when you looked from the window?’