On Friday the new lintel was installed above the office window. Yesterday we installed the new window, which annoyingly and typically, is about 1cm bigger all round than the old.
This was achieved with a lot of dust (when isn't there dust, I ask myself) by cutting back the bricks around the frame and removing another course of brick at the bottom of the opening.
Next thing to do was line the opening with some wood we just happened to have lying around the place, which was screwed into place.
Once that was done and squared to Stéphane's satisfaction the new window was slid into place, and the frame screwed to the wood lining the hole and the lintel.
All that was then left to do was make a new sill in concrete to bring the wall up to the bottom of the window.
The new window opens easier than the old window, closes a lot easier than the old window, and forms a barrier against wind and rain - something the old window had ceased to do aeons ago.