This, sent in by my friend Miss L, is another one to file under 'creepy'. I think it's the rusting window bars, which carry an air of gloomy orphanage.
Perhaps the owner of the mitten was planning a breakout and was well wrapped up in preparation, but at the point of escape was hauled back inside by a mean old matron. This sad striped number was left on the windowsill as a stark warning to anyone planning to do the same.
Found: on Arabin Road, Brockley, south London