Guys, guys lets not argue about it.
If you zoom in closely it does look like an upside down carpet, if you look closely at the edge you can see blue fibres, but I will find out as I have arranged to visit on friday afternoon so will take plenty of pictures and take up the carpet in some areas, especially under the wardrobe as it was not moved so hopefully that may help me if I can find the same problem under there!
Appreciate all your input, it has given me food for thought and a few different avenues to go down depending on what I find.
In all honesty this is what this forum is about and why it is such a great resource, carpet cleaners helping carpet cleaners.
I will report back on Friday, in the meantime, everyone have a great new year.
Tony