‘It’s bloody horrible being the passenger,’ I warned Sasha, looking down at the tandem rig laid out on the floor, ‘because you’ve got no control.’

‘You tell me,’ he said cheerfully. ‘I do it.’

We’d already had some practices during the morning, back at Balashika, but this was a full-scale dress rehearsal with all our kit on. The two PJIs who were coming with us fitted Sasha into his webbing harness, with hooks at the shoulders and at the waist, linked him to my own harness and pulled him in tight against my front, with both our full bergens strapped to the front of his legs and a single oxygen cylinder on the outside of my left thigh. Trussed together like this, carrying a lot of weight, we found it almost impossible to walk.

‘Let’s go through the motions again,’ I said. ‘As the plane approaches the DZ, we move to the edge of the deck. Let’s say it’s that line on the floor. Go on, then.’

Slowly, awkwardly, moving our legs in unison, we shuffled the short distance to the line.

‘OK. Now we’re waiting for the two green lights on either side of the opening.’ I pointed outwards at head level, right and left. ‘When we get them, and a signal from the head loadie, we just lean forward together and topple out. After that, you don’t need to do anything except hold the same position. Keep your hands crossed over your chest, like you’ve got them now. All right?’

Sasha nodded.

‘Once we’re under canopy, we can take off our masks and let them hang. Then I’ll slacken off the straps so that you slide down, about this much.’ I held my hands a foot apart. ‘That means your feet will be lower than mine, so they’ll touch the ground first. Just as we’re coming in to land, I’ll tell you to start walking. At first you’ll be walking in the air, then on the deck. OK?’

He nodded.

Without changing my voice I went on, ‘There are two other things you need to know. First, if our chute fails to open, cross your legs and keep them there.’

‘And why?’

‘So they can unscrew you from the ground.’

He stared at me, and I went on relentlessly, ‘The other thing is, keep your right hand up.’

‘Why that?’

‘So you don’t break your watch when you go in.’

At last he smiled and aimed a gentle punch at me. Outwardly he seemed pretty calm, but perhaps not, because he kept sliding off for sessions in the bog.