Last couple of nights the alarm has sounded. Been straight out and no sign of anything untoward. Is this something my pal's vcd gizmo can investigate?

Hiya mate. Mine seems overly sensitive at times. Has been set off by wind before and last week it went off twice. Went down to car and opened the door and a Moth flew out. It had been setting my alarm off haha

On a number of occasions I have had to give the inside of my car a spray of fly killer because there's been one or two setting it off.  I suppose it's good to know its very sensitive and working well!  Hope this is the problem with yours.

^^ Reasons as above.

& be sure the bonnet is properly closed and catching, wind blowing under has been known to cause alarms to sound.

 

If you look in the Service Book with those that got one and 2010/11 Fabia did, 

Alarm Sirens are due for replacement at 5 years on the Service Schedule / Guidelines.

 

Not that many get that or need it, but some do and its all about the type of usage of locking and setting alarms over the years.

eg, Lock 4 times a day a bit different from someone using a car for business and locking dozens of times a day.

Sorted (I hope!) filtering on to M4 this morning, a moth THE SIZE OF MY ****ING HAND flew into my face. Was nearly sick. Lowered glass as soon as I could & out it shot. 

Dont really mind creepy crawlies etc but didnt NOT enjoy that!!!!