‘Slow down and link your arm in mine, Detective Constable,’ said a voice clearly used to giving orders. She glanced at the man by her side and carried out his instruction.

‘Don’t look back. Just keep walking, and leave the rest to me.’

‘Yes, sir,’ she found herself saying.

‘I’m Lieutenant Sanchez of the Spanish National Police Corps,’ he said without even glancing in her direction. ‘My commanding officer had a call from a Commander Hawksby, who didn’t leave us in any doubt how important your visit is.’ He didn’t speak again until they’d reached customs, where the desk officer didn’t ask to see her passport, just saluted. Him, not her. The lieutenant chose a spot with a clear view of all eight customs posts and said, ‘Just point him out the moment you see him.’

Rebecca kept her eyes on the stream of passengers joining the long queues to present their passports to a customs official. It was some time before she said, ‘That’s him, waiting in line at the sixth box. He’s the only person who doesn’t look as if he’s going on holiday.’

‘Three-piece suit, around fifty, slightly balding, carrying a leather briefcase.’

‘You’ve got him.’

The lieutenant nodded to someone Rebecca didn’t see. Once Booth Watson had cleared customs they followed him through baggage control – he had nothing to collect – and on into the arrivals hall. He hurried out of the airport and joined the taxi queue.

Rebecca noticed a young man slip into line behind him. When Booth Watson eventually reached the front of the queue and climbed into the back of a taxi, the young man made a note of the number plate, but didn’t jump into the next cab.

‘Isn’t he going to follow him?’ she asked, trying not to sound desperate.

‘Can’t risk it,’ said the lieutenant. ‘Your chief made it clear that if the man you’re after thinks he’s being tailed, he’ll head straight back to the airport, and your journey will have been wasted. But don’t worry, we have the details of the taxi driver, and we’ll interview him later and report back to Scotland Yard to let him know where he dropped off your man.’

‘What if he switches taxis?’

‘He’ll find the next available one is one of ours,’ he said, looking across the road and nodding.

‘So, I’m nothing more than a messenger,’ said Rebecca.

‘A very attractive messenger, if I may say so, señorita.’

‘You wouldn’t get away with that in PC England,’ said Rebecca, smiling.

‘Ah, but you are now in Barcelona, not England.’

‘What am I expected to do now?’

‘You have been booked on the next flight to Florence, where your boyfriend will be waiting for you in arrivals.’

‘How did you manage that?’

‘I think your boss felt guilty about interrupting your holiday,’ the lieutenant said, as he handed her a first-class ticket to Florence. ‘I hope you have an enjoyable time in Italy, Señorita Pankhurst. My grandmother was a great admirer of your ancestor, although it took my countrymen several more years before they finally gave women the vote.’ He saluted, and had departed before she could say, ‘In 1931.’