All the thoughts about Dan that are counter-productive, as he hasn’t called me since our date and the almost-kiss. I might be out of practice at dating, but I definitely know what that means.

Bear starts barking when we’re still half a dozen houses away. Isabel must have been waiting for us, because she appears instantly at her Farrow & Balled front door.

I let go of the dog’s lead and he runs towards her, his tail wagging so hard it could power the entire street.

Before I met my mother-in-law I had an image in my head of a well-upholstered farmer’s widow, all dimples and cuddles and floury hands. Instead she was wiry, with toned arms and scarlet shellac nails. We had nothing in common except Andrew, and it was only when he got sick that we started to bond.

‘Someone is about to explode with excitement!’ Isabel says. She’s immaculate, as ever, her petite frame draped in an expensively cut peach jersey jumpsuit. She’ll be sixty later this month, but she could be mistaken for at least ten years younger.

I close the gate behind me and Isabel lets Bear jump up and down. ‘Yes, I adore you too!’ It’s good to see her laughing. When we met at Christmas, even her expensive serums couldn’t disguise the devastation my latest failure had wreaked.

Bear gallops onto the patio. The Moroccan table in the conservatory is laid for lunch, including wine glasses and a jug of iced water with mint. On the other table lies a half-finished jigsaw, a complex Klimt painting in shades of blue and gold. Andrew got his love of puzzles from his mother.

Isabel brings through a quiche on a marble platter. ‘From the deli – I swear he uses unicorn tears to make this pastry.’

When she returns with a bowl of spiky coleslaw and a bottle of chilled Chablis, I let her pour me a small glass that I won’t drink. But I don’t feel like telling her my news until after lunch. Must keep to safe topics.

‘That one looks hard going?’ I say, nodding at the jigsaw.

‘I’ve been neglecting it a little.’ When she smiles, there’s a hint of secrecy on her pink-frosted lips. ‘I take it there’s still no sign of Andrew’s puzzle?’

For a while after he died, Isabel became obsessed with the idea that her son had hidden some kind of jigsaw or riddle in the flat for us. Apparently he told her he had when she sat with him one night, near the end. I’ve turned the place upside down, but there’s no sign, so it must be wishful thinking on her part: a lot of what he said in those last few days made no sense.

‘No. But I always keep an eye out for it.’ I cut into the quiche. ‘You’re right, this smells heavenly.’

‘Are you eating enough? You look weary, Gemma.’ She scrutinizes me with those light-blue eyes and they’re so much like Andrew’s that I have to look away.