Project 365 day 270: Shield Bug

I found this little brown shield bug on a very large, running to seed chard plant which I was pulling apart to remove the remaining edible leaves. I was particularly taken with the way the sun caught the coppery teardrop shaped patch at the base of the shield. I don't know what kind of bug this is, despite looking at a couple of websites, so help with identification would be welcome.

The morning was wet, windy and chilly. I decided autumn had finally arrived and got out my woolly tights. By mid morning I was out on the deck under brilliant blue sky with small fluffy clouds drifting low and well separated above the Downs. After lunch I took my laptop to the balcony and felt the warmth of the sun on my back as I composed a rather difficult email and updated an over-long to-do list. After J's PA left, we enjoyed more of out "mufferoles" together, then I left her searching card ideas on Pinterest while I picked another tub of raspberries, two more cauliflowers and two more cucumbers. Not a bad day.