A piece of aluminium was cut and screwed to the frame so as to allow the catch strike it and pull the outer frame in to the inner frame. The curvature of the frame still prevents the window from closing correctly however it is a lot better than it was previously.
The same was done on several other windows and one in the lounge had new catches fitted. However that one now has the top of the window pulling outward from the frame.
The contractor seemed to think that the reason the windows have bowed is because of the lateral movement in the house however he has never seen this before. I then showed him a window that has cracked in the corner and is behind the couch in the living room. It looks like the frame has moved sideways causing the window to flex and crack.
He voiced his concern as apparently any windows at that height should have been replaced by safety glass and eh stated that we were lucky that we had something over the window. I then showed him a window that was replaced around 4 or 5 years ago and he stated that at that time it really should have been replaced by law with safety glass as it is below a specific height.
The contractor finished up his work and stated he would make notes of the cracked glass, safety glass and problem with the frames.
I did not get to examine the work before he left however after taking a look was surprised that he had not cleaned up after himself and had left aluminium turnings in the window channel, on the window sill and on the floor.