‘The wee bird has flown, sir. The house manager confirmed that Gus van Steenis left on Friday afternoon to catch a flight to Harare.’

Gillard cursed under his breath. ‘So we were already too late. Never mind, let’s search this place from top to bottom.’

A team of thirty officers began combing through the zoo, aided by the staff and keyholders, while Gillard sat behind van Steenis’s rather grand desk and started checking up on flights to Harare. He made some progress quite quickly, discovering that Zimbabwe was a signatory to the 2003 Extradition Act. Of course, that may not be van Steenis’s final destination. He was an old Africa hand and there must be many places on that continent where he would be welcomed. The detective was just making his second call, to British Airways to see if van Steenis had been on Friday night’s flight to Harare when a grim-faced Rainy Macintosh walked into the office.

‘I think you better come and see this, sir.’

Gillard ended the call and followed her. She led him around the back of the main building to a large ugly barn. Officers had already forced the corrugated metal door and switched on the light. The entire shed was turned over to tools of various kinds, ancient and modern. Spread right in the middle of the shed was a large plastic dust sheet, and on it a gym mat.

‘The bastard built an electric chair, probably for Rollason,’ she said.

Gillard walked over and inspected the hefty hardwood chair with buckled canvas restraints on its arms and front legs.

‘Just pop yourself on here, Detective Constable,’ Gillard said. ‘I just want to check if it’s connected.’

‘With all due respect, boss, kiss my arse,’ Rainy replied cheerfully. The male uniformed officer by the door, who had been chuckling at Gillard’s suggestion, gasped at the Glaswegian’s insubordination. Gillard playfully pinched her cheek. ‘What would we do without you, eh?’

‘Shocking behaviour, sir,’ the male uniform ventured.

‘Don’t you start,’ Gillard retorted.

‘It’s clear van Steenis went to a huge amount of trouble, but never got to use his wee chair,’ Rainy said.

‘How do you know?’ Gillard replied.

‘Have you ever read accounts of the effect of electrocution on the human body?’

‘No, I haven’t, but I’m sure you’re going to tell me.’

‘I dealt with a man who was badly burned trying to steal part of the live overhead cable going from Shotts into Glasgow Central. Aye, he wasn’t a pretty sight. Not to put too fine a point on it, sir, you’d never get rid of the smell of piss and shite from this place, if van Steenis had used his machine.’

‘Point taken, Detective Constable. Trouble is, someone did kill Rollason. If van Steenis had hold of him why didn’t he use the chair?’