Something in the air

The other day there was a very strong smell coming from our front room. We called Transco, who came out within 15 minutes and very efficiently performed a number of tests involving funny little bits of tube and beepy machines. No gas.
Today, after nothing for a few days, the smell returned with a vengeance. I was advised to call up again should there be any more problems - better safe than sorry.
But this time, the man who walked through the door took one sniff and said "You've got something rotting somewhere. That's definitely the smell of decomposing matter."
What matter? Where? Oh no! Surely not the Amorphophallus Titanum lurking in a corner somewhere?!



He did all the gas tests again, which were of course clear, so confident was he of his theory, and off he went, leaving us with something rotting, somewhere.
Where? I need to know now. This is most disquieting.
"It'll probably get worse in warm weather," he added with a grin before departing, "but it'll go away eventually."
With temperatures predicted to top 100 degrees this summer I could only despair.
We have a dead something, somewhere, and I'm not sure how to get to it.
"It's more than likely to be a rat under the floorboards, but unless you want to take the whole floor up..." he sighed, shaking his head as he went on his way.
OF COURSE I want to take the whole floor up. Get the thing out of here. Now!
I imagine my only course of action is to phone the environmental health department. I just don't know what priority they attach to the removal of dead mice/rats/pigeons/former tenants/Amorphophallus Titani, or whether they have the time to come round and take the whole floor up.
It's just so strange, the way the smell comes and goes.
Maybe we have a poltergeist. Or a poltergeist Amorphophallus Titanum. Now that would be something to behold floating around the room.