Slate roof gutter between neighbours

[Alan51]

Got a quote for my roof to be refelted with breathable felt, new battens and the original slates reattached with recon slates where needed. Needed as no ventilation to the roof space and numerous slates have slipped.
My slates are a completly different size to the neighbours and the tie in is terrible so roofer has said that the slates will need to be cut and a gutter will be needed between the houses as the slates can't be tied in successfully due to the different sizes. I can see his reasoning but does it sound correct to more knowledgeable people.

 

[mattylad]

Do you not currently have a gutter?
A photo would help understand the situation better.

 

[Alan51]

Do you not currently have a gutter?
A photo would help understand the situation better.

I'd struggle to get a photo as it's on the roof. The problem is the slates on my roof are a different size to the neighbours so the tie-in is a mismatch of overlapping slates. The roofers solution is cut a line through the slate along the party wall from the chimney down to the gutter and have a channel that would catch any water. So my slates would stop and the neighbours would start, they wouldn't overlap each other.

 

[datarebal]

That is perfectly ok. If done properly

 

[Alan51]

That is perfectly ok. If done properly

'If done properly' there is the age old problem.
I'm hoping this should be done properly as the roofer has done a lot of work in the area and has a good reputation.
I might just be being nervous as this is a lot of money for me to spend.

 

[datarebal]

If he is known locally then it should be fine.. it's not difficult