Buying a house with a boundary that could be disputed

Land_Registry

Whilst mistakes are made both in conveyancing and registration the post that worries me is the one which states
'The title shows the house with land as it is.. the land registry shows a slice of land on one side being on the neighbours plot'

A title plan only shows the registered extent for the title it refers to. It does not show what next door owns.
When I read posts such as this it is usually the Ordnance Survey detail the poster is referring to. The OS black lines don't show legal ownership. They refer to the physical features in place at the time of their survey. The red lines added by us show the registered extent/general boundaries.

So as suggested you start with the title to the property being purchased. Your solicitor (not us) asks you to check and compare it with the reality on the ground.

If it does not match then they raise it with the seller and it seems they have done that and they have replied along the lines of don;t worry as we both agree that strip of land is actually the sellers.

Most solicitors would advise you against completing and would ask the seller to resolve it. A resolution depends on how the 'error' occurred.
If a conveyancing one then I suspect the land will have to be transferred from the current registered owner to the seller
If a registration one then an application could be made to correct the two titles and if we agree it was an error on our part we may correct it providing the current registered owners agree. If it wasn't our error then back to first option.

In some cases there was no conveyancing or registration error but at some point a fence was moved so one party lost land and another one gained it. OS may never have revisited to survey again as no new development etc so you have what you have now.

So plenty to ponder with your solicitor but it is their advice you should rely on here as they will have the details, appreciate and understand the seller/neighbour replies and be aware of the risk(s) involved and which others have posted.

It's that detail that should help you decide whether you complete as is or ask them to sort before you do. If you were buying with a mortgage then your lender is likely to say No to proceeding anyway but if a cash buyer then down to you/your solicitor.