Adverse possession/ flying freehold-trying to sell!

[Flantastico]

Anyone with any advice here please? Getting stressed Partner accepted an offer on his house back at the end of last year. When he bought it 10 years ago,the conveyancing solicitors said part of the property (upstairs bedroom overhanging an unregistered alleyway below) was flying freehold. However during the course of this sale,the new conveyancing solicitors have said that this part of the house is outside of the property boundary and he needs to apply for adverse possession.
He's contacted the old solicitors who are adamant that it's flying freehold and they are recalling the files from the vault to show this. Meanwhile the new solicitors are recommending an indemnity policy.
Surprisingly the buyer appears happy to proceed with the purchase but I'm getting worried because of the discrepancy between what the two solicitors are saying. Has anyone had any experience of something like this? Is there anything we can do?
Thanks in advance.

we have a 'flying freehold' in our house, but its my (semi detached) neighbour who has the upstairs room and we have the groundfloor

i've attached a MN diagram

caused a little extra work re mortgage

Hi Sussex. So no big deal then? Did some reading and got worried about the availability of mortgages on properties with F2F and AP. (PS loving a MN diagram )

for us it wasnt, i cant quite remember the details, it was 10 years ago

Thank you,that's reassuring

We used to live in ex council houses where they had rooms over the alley between the houses, we had back bedroom over the whole alley, neighbour had front bedroom and we each had half the alley front to back iyswim.

It wasn’t a major issue. We got first mortgage with local regional building soc and then remortgaged with Nationwide a few times. When we sold it wasn’t an issue either and the buyer got a mortgage with no hassles. A couple of lenders wouldn’t look at it but there were still plenty to choose from.

Thanks nerd,good to hear another reassuring report. Hopefully all will go smoothly for us too