When the bottom of the frame was at waist-height, the four techs lifted it off its chains and lowered it gently onto a set of foam bricks, then rested for a few moments before placing it into a specially prepared travel frame. This unique piece of craftsmanship had been constructed by a carpenter who’d never seen the canvas, but had been supplied with the exact measurements of its ornate gilt frame.

Once the painting had been fitted securely in place, a protective layer of polythene was stretched taut across the surface before the team of technicians, supervised by Mr Benmore, manoeuvred the travel frame into a fortified external crate, constructed by the same carpenter; a delicate undertaking that required skill and strength in equal measure. Mr Benmore’s final responsibility, after checking there could be no internal movement during its long journey to Barcelona, was to securely fasten the crate’s wooden lid with an electric screwdriver. Ross counted all twenty-four screws.

After a thorough inspection, Mr Benmore declared himself satisfied, and allowed his team a tea break.

Twenty minutes later, they were back in action. Two of them lifted the crate a foot off the ground, while the other two positioned a wide skateboard underneath. After the crate had been gently lowered onto the skateboard, it was wheeled slowly out of the dining room and along the corridor towards the front door. Correx sheeting had been laid out along the route to protect the marble floor.

When they reached the entrance hall, William glanced across at the laird, his arm around an elderly woman who he recognized. She was holding back tears for the dear departed.

He noticed that the painting remained upright from the moment it was packed into the crate, until it was strapped into place in a climate-controlled, air-ride suspended truck, to ensure that the Fishers of Men couldn’t fall out of their boat.

They never exceeded thirty miles an hour on the twelve-mile journey to Aberdeen airport.

William and Ross followed behind in an unmarked police car. A private jet awaited them at an airport where private jets are more common than commercial aircraft.

Mr Benmore was the first out of the truck, and once again he supervised the technicians as they painstakingly transferred the painting into the plane’s hold, where it was strapped in – still upright. He and the insurance broker never took their eyes off the wooden crate until the door of the hold was heaved into place. Four passengers climbed aboard a jet bound for Barcelona.

When the plane landed on Spanish soil a couple of hours later, they found Lieutenant Sanchez waiting to greet them on the tarmac.

He was equally well prepared. Under the anxious direction of Mr Benmore, four policemen in overalls unloaded the crate from the hold and strapped it upright into a padded, temperature-controlled van.

Ross sat next to Sanchez in the front, while Mr Benmore, Mr Posgate and William climbed into the back. William tapped the divide, and Sanchez set off at a funereal pace for the final part of the journey.