Before I forget...
Our original plan for windows was to go for a t-shape, as we had one old window at the back that was in this form, so we thought it might be more "original". However, looking closely at the old photo we found, the windows used to have eight panes (check out the one on the top right).
Anyway, we wondered what it might look like with eight panes, having moved on to six after the original t idea.
We could try to mimic the eight panes with a t using wider pieces, and then have narrower cross-pieces below, but I think it might be a little too much. Opinions?