Martial law?

I was surprised to see this at the lights - I wondered whether martial law had been declared while I was in Morrisons. It also reminded me of seeing tanks on the streets of Germany in 1989; they were a regular sight in some towns with military bases. I always thought that the six foot stalk with an amber light at the top might be a bit of a disadvantage should the Soviet army have decided to roll through the Bundesrepublik but I'm no military planner.