It's a right pain in the backside.
There is a width sign which my car is clearly well within before the narrowing but i've measured it and although you can pass the poles on either side without mirror contact, it's almost impossible to get through the gap without the wheels catching the raised kerbs, probably half an inch at most to spare either side and it's on an angle so you cant get lined up 100% straight on.
It's only been there for a short time and already looks like someone has been at it with a pickaxe with chunks and scuffs on the kerbs.