Caporn's spot, for the Office of the Deputy Prime Minister, highlights the importance of frequently checking household smoke alarms.
The ad, "forgetful man", compares the consequences of relatively trivial oversights, such as forgetting a mobile phone, to forgetting to check batteries in a smoke alarm.
It finishes with the line: "Test them every week, change them every year. Push the button, not your luck."
The award was judged by Chris O'Shea, the executive creative director at Banks Hoggins O'Shea/FCB. The runner-up was a spot for Durex, "unavailable", created by Chris Forbes and Carol O'Shea of McCann-Erickson.
Chris O'Shea said: "Sometimes less is more. This ad for fire alarms caught my ear because of its simplicity. Simply written and simply produced, it simply had a single voice reading a witty script, which suddenly changed into something quite ominous.
"I'm sure it stood out wonderfully on your average music station."
The winners of the monthly Aerial Awards are put forward for the annual awards ceremony held later in the year. Winning ads can be heard on www.aerials.co.uk.