Roof Construction

[minesapint]

I live in a detached house built from conventional orange coloured bricks. The roof of the property is tiled.
On the side walls of the house, there is a layer of a grey coloured material between the last brickwork course before the roof and the tiles of the roof itself. To all intents and purposes, it fills in the gap between the brickwork and roof tiles.
A section of this material has dropped out of position and is hanging down the wall like a large, fat sausage, leaving a gap between the bricks and roof tiles.
Can anyone tell me what this roof section is called and what is the material made of.

Thank you

[buildersmate]

If it is on the sloping part it is known as the verge.
What you seem to be describing is often called undercloak. In the old days it was made from asbestos cement sheet - now it is glass-reinforced cement board. It sits on the top edge of the brick and allows the edge roof tiles to hang over a bit - alowing a slight slope back against the roof and forcing any water that does come over the edge to drip harmlessly to the ground - not run down the brick.

[minesapint]

Many thanks buildersmate. It is on the sloping part of the roof. I've just had a look at a few pictures of roof construction on the internet and most show what they call a barge board covering the gap between the tiles and brickwork.
In my property, there are no bargeboards, just this grey stuff filling the gap. The house was built around 1972.
The stuff seems to have been trowelled into the gap somehow and it doesn;t look like any sort of sheet or board as it's not proud of the brickwork.

[minesapint]

Incidentally, the edge roof tiles do not project over the gable wall. They are flush with the wall vertically.