I noticed recently that these two glass windows in our front door had become a bit grubby, so I gave them a quick clean.
They are known as 'Bullseye' panes, and they originally date from medieval times.
It reminded me that recently one of our neighbours posted something on our street's WhatsApp page that was quite worrying.
He said that on a hot sunny day the sun had come through the glass just like through a magnifying glass, and had begun to scorch his stair carpet. He suggested we all put a curtain behind the glass to prevent all our houses catching fire.
Well I didn't put a curtain up, and am relying on the fact that for the past 60 odd years, since the house was built, that not one house in the street has caught fire, and I pray this will continue.