Edith is enjoying the ride.
'I'll be 90 in September. Guess what day I was born. Know your history?'
I try to think of famous days in September. Armistice? That's November. VE Day? Agincourt? I try them out on her.
'I'll give you a clue. September 11th.'
'Oh, well,' I say, 'September 11th, of course, the World Trade Centre. Terrible.'
'September 11th, 1916. A Zeppelin came down in Cuffley. Shot down, by a Mr Robinson. My father was there. He saw him do it.'