About 15 '.

As much as that, Spritz, ours have been at about 1m for a number of years now.

I went by the RHS book, Mr MB. Mine's only 3 years old! I have seen larger ones, though.

Mine's about 12ft, I think. I cut it back a bit because it was overhanging the neighbour's garden. I can let it go now there is no fence. I'm sure it will make 15ft.

Thanks, Volval - I started to wonder then! :-))

I might have been a little rude to ours but they are certaily less than 2m. Maybe we have a dwarfer form? I hope so because I wouldn't want them to get to 15ft.
We have two and they are currently bearing floury, yellow catkins. Sometimes they also have nuts.

They are slow growing for the first few years. Mine is about 20 years old but only grew faster in the last 5 years. It does have lots of nuts. Only started that in the last few years, too.