Hmm, thought about it a bit and the bright sign made by the candles is a CND one , campaign for nuclear disarmament, a British anti-nuke lobbying group.
The shot in the ad, was prolly picked from one of thier anual rallies.
Thier motto is no to nukes, no nukes, no final war, the candles might prevent a future war. Since it's all nukes now.
Or is it alluding to the arms race, tho that was dealt with with in two SALT treaties between Reagan & Gorbachev, seems a bit anachronistic nowadays. Whatever nukes that remain are to maintain a sufficient deterrent. The other bigger factor is they have become a lot more accurate and smaller in size.
..maybe that's what the ad was trying to reach for.