The windows are very old and seem to be bowing and getting misshaped. I dont think the can handle the weight being applied to them. Could this be caused by inadequate support from the windows?
check around the gullies for any gaps, or cracks, also any cracking in the path is an indication of drainage problems, causing subsidence. The cracks in the photos don't look too worrying at the moment, I would cement a glass slide over the crack to see if it gets worse.
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