How do I know if I’m responsible for upkeep of whole of neighbouring wall?

[MacmillanDo]

We have lovely new neighbours. In passing they mentioned that the wall between our gardens is our responsibility - according to boundary line on whatever they’re looking at.

We’ve never considered both sides were our responsibility - how do I go about checking, understanding and responding?

Thanks

Check the title deeds https://www.gov.uk/get-information-about-property-and-land/copies-of-deeds

It may show up on your house deeds, the boundary will be marked in red, it might also be documented on the sellers form from the people you bought it from. Try the land registry and your title deeds.

So, here's a screengrab from the title deeds. My house is in red. What does it tell me? Sorry if I'm being obtuse.

The red is inside the black line, I think - does this mean I am responsible for my side?

@MacmillanDo No of course you arenot being obtuse .
It's often not clear who has responsibility for maintenance .
The title deeds (rather than the title plan ) from the land reg may mention or show T marks eg on the northern boundary .
But there may be no marking and no mention .
‘T’ and ‘H’ marks do not usually appear on Land Registry Title Plans. Rather, they are often to be found on deed plans.
Where T marks are shown they indicate boundary structure ownership or responsibility, the side of the T indicating the responsible side of the boundary. H marks or 2 T marks back-to-back, indicate shared boundary structure ownership or responsibility.
I think I'd download the title deeds for your property and also for theirs .
If unclear I'd go back to neighbours and explain it seems unclear on documents for both properties and could they explain the position to you .
Or polite words to that effect.

If there's still soubt then your conveyancer can find out for you

Yes, as @allamberedovermentioned, sides marked with T will be your responsibility. Do you have more detailed plans?

I was surprised that I was responsible for all 3 of my garden fence sides when one fell due to winds! That was annoying but guess it was in the plans!

I'm going to order more detailed plans... thanks all