This is a nicely written little ficlet- you're confident in your writing and have a talent for little details that bring ficlets like this alive.

I found that you did stray into telling rather than showing a few times. For example, you don't tell us what Charlie said to Bree, only that he said it :)

The speech tags toward the end were a little confusing to me, as they didn't have the punctuation speech usually does- a capital letter and a comma or period at the end.

The ending was lovely, but I thought it could definitely do with a bit more detail and rounding out. I'd like to know more about Mark and about arriving at Hampstead Heath. :) Anyway, well done!