The photos above and below show the top corner of the quarter light opening (window open). A short section of rubber seal (different from the main seal on this window) is covered by leathercloth, but partly revealed due to slight damage. The black felt on the window frame pillar should extend up to the top.

The view from the inside of the quarter light top corner. I've peeled back the leathercloth to reveal the rubber seals. I'm also pulling back the top end of the main rubber seal (that runs down the front of the window opening) to show where the two seals meet. The top seal has its beading trimmed down to clear the window top bracket. The inner edge of the leathercloth is normally clamped under the varnished wood trim (not shown here). Its outer edge is clamped against the rubber seals by the glass when the window is closed.

Here is the leathercloth in place with the window closed against it.

The leathercloth has broken away to reveal the main seal's fixing flange. The seal's flange is tucked into the door frame rebate and tacked into place.

The outside of the quarter light showing the main seal that extends as far as each of the window brackets.