Selfridges sells Aunt Jemima, imported of course for the lowly sum of around £7.50 per bottle!
I've seen Canadian maple syrup on the shelf at Sainsbury's...but again it's very expensive, around £4.50 for the small jug-like glass bottles.
Closest and best priced I've found is in Golder's Green at the Yarden supermarket, they've got, I believe it's Osem maple syrup. It's hard to find if you don't speak Hebrew, as the label has the word "Maple" written in Hebrew (transliterated, not the actual Hebrew word for maple). It's in an orange bottle and has a picture of pancakes on the label, goes for around £1.75