Hmmm, possible?

[BDG]

A whole city or town is not going to burn down in the UK due to an accidental fire, or even a deliberate, perhaps dozens of deliberate ones. A block of linked buildings may, but as compared to the large fires we know of in history that destroyed cities, the cities back then were made out of much more flammable materials and contained many things which you are just not allowed to store in any great amount in built up areas.

However, in the event of an EMP attack, fire could be a friend to a lot of people wanting to reduce numbers of people or control their movement. In the event of an EMP I would expect to see a number of gas explosions as fail safes in gas equipment do not work. These would need a source of ignition - normally an electric spark and anyone with any sense would turn off the gas and ventilate.

The odds I think at the moment of an EMP are slimmer than former members of The Carpenters.