I followed her down the lane like a reluctant toddler following her mother, kicking the ground as I went.

‘There are two parts to Highgate Cemetery, East and West,’ said Marcia. ‘I think the East one on the left has more recent graves, so the West side is the one we want.’

‘How do you know if she’s buried here and, if she is, where she’ll be?’

‘This is the main cemetery for the area, so there’s a good chance that this is where her grave is.’ Marcia pointed to an eccentric-looking building further down the lane to our right. It appeared to be a mix of architectural styles, with Tudor windows, Victorian turrets and a Gothic-looking wrought-iron gate in the middle. ‘There must be a records office in there. We’ll go and ask.’

‘I’m not going,’ I said. ‘What are you going to say if they ask how you knew Grace? The truth would sound bonkers.’

‘You stay here then,’ said Marcia, who went up to the office and knocked on the door. As I waited, I looked around in awe. The place was straight out of a Gothic movie, with many of the gravestones worn or broken, overgrown with ivy and moss. Some had Victorian statues marking them. Behind the entrance and across the courtyard behind the office was a colonnade that looked like the front of a horse’s stable, only made of stone.

Marcia came out a moment later. She gave me the thumbs-up. ‘The lady in there suggested that we talk to one of the guides. We have to pay to get in and go round with one of them. The next tour is on the hour.’ She glanced at her watch. ‘That’s in ten minutes. You up for that?’

I shrugged.

‘Good,’ said Marcia, ‘because I’ve already got us tickets.’

We noticed a bunch of tourists gathering by the gate and went to join them. We were soon joined by our guide, an elderly man with sandy-coloured hair who was wearing an old cardigan and cords. He introduced himself as Nigel, then indicated that we should follow him into the wood.

‘The West Cemetery opened in 1839 as one of the seven new cemeteries,’ Nigel told us as we walked down the moss-covered paths. ‘They were known as the Magnificent Seven.’ As we trooped along with the group, I stopped to read some of the inscriptions along the way:

To Edna, beloved wife.

For Marcus who fell asleep.

Forever in Our Hearts Agnes.

Or simply John Richards RIP.

‘What do you think you’d like on your gravestone?’ asked Marcia.

‘Cheerful,’ I said. ‘I’ve never really thought about it. You?’

‘Nothing. I want to be cremated and my ashes scattered down on our favourite beach in Dorset, or in our garden with a tree or flowering shrub planted to mark the spot.’