I finally got around to fixing the window - been putting this off since we had the window replaced. When the window guys removed the old window, half of the plaster wall came with it. Nicely tucked away behind some architrave, it needed to be fixed.
Rather than plastering around the architrave (an option) we decided to pull off all the plaster, put up some backerboard and tile the wall instead. Given the placement of the shower door wall, the architrave could have only gone around 2/3 edges and wouldn't have looked symmetrical (see picture).
So in the spirit of "it going to look worse before it looks better", I took off all the remaining plaster down to the brick wall. And in doing so, I found the old lead over flow pipes. One went up to the loft cistern, the other was just terminated. You can see the picture of the pipes from the outside (not the most attractive feature of the house). After some cutting, hammering, pulling, nudging, swearing ('cause it helps), and more coercing, the pipes finally came out. They left a fairly large hole behind however. Good thing I'm now an expert with spray foam. I applied a much less generous amount this time and the hole was nicely plugged.
The wall behind has seen better days. The masonry needed to be smoothed out to fix the backerboard. After adding wood supports, bonding plaster and some chiselling, it was finally ready to go. I applied a coat of SBR diluted 3:1 with water as a bonding agent/moisture guard and fixed the aquapanel with tile adhesive. After this set, I put some frame fixer screws to hold it in place. The final result was mostly flush - the rest I could smooth out with the tiles.
In place of the architrave, I decided to use a tiling corner bead. I fixed this to the uPVC window frame using some mitre glue. I suspect that this is really super glue in a more expensive package. But hey, it did the trick and felt like I could do pull-ups on the new bond.
Finally, came the tiling. Given the irregular border of the window frame now, this involved some creative tiling. I bought a special Dremel attachment a while back for just this task. It's basically a rough stick that goes on the end; but it just eats away tiles and made my job easy. Recommend this for anyone doing intricate tiling. The overall job looks fantastic if I can say so myself. Really nice boarder around the window now and will show a treat when I get around to the grouting.