Im glad to see some other 05 reg have the roof aerial, was getting a little worried. I have taken these pictures, after inspecting the rear window last night there are only two elements that arent connected to the heating matrix that could be aerials, I hae tried to capture them in the very dusty picture below
It can be just seen as the second line of wire running above the heating matrix.
ANd secondly the picture of my roof aerial, looks to be exactly OEM and in the exact position.
Only thing I can think is that a small number of 05 reg cars were the start of the roof mounted aerials. Those without roof mount, does the filament in the rear window the same as yours? and others witht he roof mount 05 can you see if you have the same filaments as in my photo, it comes in from both sides and has a break in the middle which is off center.
Jaffa you have got me thinking and until this morning worried that strange things had been done to my car!