They followed her. Having dropped her children at school, on foot, the woman went to a cafe and one of de Payns’ technicians followed her in and sat at the neighbouring table with a spinner the size of an iPhone to confirm that the woman was carrying the phone.

De Payns also had a filature planned for when she left the cafe. The filature entailed a team of five people putting the woman under surveillance and reporting in real time back to the sub, where de Payns sat with the DT operatives.

Before she left the cafe, de Payns checked everyone was on the net.

‘Y radio check,’ he said into the mic on a necklace under his T-shirt. The activation button was in his pants pocket.

The confirmations came back, one after the other. ‘Jéjé’; ‘Danny’; ‘Paulin’; ‘Vehicle’.

De Payns confirmed he was hearing them. ‘Okay Y. Loud and clear. Jéjé, you have the alert.’

‘Jéjé. Copy.’

Jéjé was a former naval diver who’d been recruited into the DGSE in his late twenties. He was smart and tough and the operation would start at his lead.

After forty-five minutes of radio silence, Jéjé broke into de Payns’ earpiece.

‘Alert, alert, alert,’ he said. ‘Target. Brown jacket, jeans, black handbag. Just exited the cafe, walking south towards Place de Vannes, on Borgnagache, odd number side of the road. Coming towards you, Paulin.’

‘Aguilar copy,’ said de Payns. ‘We’re moving to de Vannes.’

As the sub started moving, the filature actively communicated.

‘Danny copy. Visual. On the other side of the road. Keeping visual.’

‘Paulin. Copy. I’ll take Echelon 1 when she walks past.’

‘Vehicle copy, on standby,’ said the driver of a small Citroën. Her passenger was ready to alight from the car and pursue on foot.

‘Jéjé. Going to the Mons Metro. Danny, you stay at Echelon 2 after Paulin takes her.’

‘Danny, copy.’

‘Paulin. Visual. I’m on it. Turning right from Borgnagache onto Place de Vannes, opposite way of the car flow, even numbers side of the street, level with number forty-two, walking slow.’

‘Danny, visual.’

The sub was now heading towards Boulevard Charles Quint, which looked down towards the Mons Metro station.

‘Aguilar. Boulevard Charles Quint, anticipating target.’

Twenty seconds later they could see the target in her brown leather jacket leaving Place de Vannes. She was into Boulevard Charles Quint and turning left for the Metro.

‘Aguilar. Visual on target. Walking south on Charles Quint towards Mons Metro. Odd numbers.’

‘Jéjé, pre-positioning Mons Metro,’ said the former frogman.

De Payns said, ‘Aguilar for vehicle, drop one pedestrian at the Mons Metro on south line.’

‘Vehicle copy,’ came the response.