BIG "EXPLOSION" HEARD IN AREA TODAY

At around 4.15/4.20pm today there was a loud 'boom', a crashing or exploding noise heard that was so loud it shook windows and set off car alarms in a large-ish area around the canal near Little Venice.
The loud noise wave was pushed in many directions by the areas buildings and rattled the windows on either side of some houses, so it was too hard to place the scene of the "explosion" as coming from any one direction.
Although the noise had the residents of one street all out in their slippers looking for the cause they found none, there was also no reaction from the emergency services that anyone noticed, no sirens were heard afterwards and there wasnt any rising smoke seen, nor any 'on a mission' Police presence.
The area around the noise has terrible problems with blocked drains, every year when it heats up and the rains stop the smell of the build up can over power, a gas build up is very possible, in some parts of Shirland road the blocked drains leave a smell that hangs around, like a...a bad smell (that joke should be arrested). a gas leak cant be ruled out as being the cause either, one caused by workmen digging up the road (-again).
It's just strange that such a loud bang, one that rattles windows and sets off loads off car alarms wouldn't get a noticed reaction from the services, despite Police stations, a Fire station, a Hospital and Ambulance crews all being situated locally and easily heard during much of the day.
There is of course also the paranoid reason that is usually given by someone, that it was a bomb or an experiment of some nefarious kind that the government wanted 'hushed up' for moral, legal or 'ongoing-undercover MI5' reasons.
As Im writing this the reason behind the noise hasnt become known, yet. Will we have a genuine modern mystery in our area? Big urban 'Booms' with no apparent cause have happened before, along with other mystery noises, is this one? Only time, local TV news and/or the local papers might or can, tell.
Lets hope The Sun doesnt find out, otherwise residents will be finding mutilated cows in their gardens and the workers of Clifton gardening centre will be finding crop circles in the busy lizzies.