Replace and level a window board (interior sill)

This was a job that you might think "why?" because the window board looked ok before I changed it. What was noticed was that when the curtains were closed there was a big gap between the curtain and the window board at one side of the window but not the other. At first this was put down to the curtains but some investigation revealed that the window board ran 15mm out from one side of the bay to the other while the ceiling ran 10mm out in the other direction. This meant that in total the gap between the ceiling and the window board was 25mm more on one side than the other. So, strip out the old board, level up the brickwork and fit new. Could have reused the old board to save money but the end corners were a bit battered and the internal joints were badly cut so replacement was the answer. There's a separate article coming on the replacement of the curtain rail and dealing with the ceiling run out