Joining terrace roof gap?!

Hi, we live a mid terraced house (one of a block of 4) build around 1930's. Our next door neighbour (one of the end houses) has just had a new roof, however the point at which their roof joins our roof now has a 2 inch gap running from top to bottom (back of the house only; the front of the house has been sort of "jigsawed" into our roof. The gap was covered by lead flashing before, but there is nothing their now (just some kind of plastic / flet strip under the slades that bridges the gap between the two slade edges). I have looked at other houses around the estate and they don't seem to have this gap.

Is this type of gap normal?

If not, how do I go about get it rectified as it was perfectly fine until the new roof was done I don't see why I should foot the bill?

Any info, view points or suggestions would be greatly appricated.

Thanks.

i would tell your neigbour he has a very nice roof, but when are they going to finish it?

when he says it is finsihed, then ask him round to yours and point out the error, saying it was ok untill he had new roof.

i did the same to my neighbour, 2 days latter new leadflashing (although it was not a roof on the top, but an extension roof most of us here have)

the plastic strip you speak of,should be a fibre glass bonding gutter.it is used to join two roofs with different profiles together.the gap between the two should be about 50mm.the tiles either side of it should be bedded onto it with mortar.my question would be why have they done it on one slope but not the other .