What the jimminy is going on with my cabbages?!?!

They're growing so tall they almost resemble sprout plants.  Could they be bolting?  A fellow plot holder tells me he thinks it's because the net I'm using (very fine blue mesh) has the same effect a greenhouse would.  I am given to thinking this gentleman might be talking from a body part, not designed to give gardening advice. 

Is the blue netting giving too much shade for the cabbages ?

My cabbages go under blue net and I have never had a problem. Maybe it is just the variety.

Mine grow under green netting with no problem - I think it's more likely due to the weather than the netting.
Plants in my garden are much lusher than normal this year.

I think your right there Mum , mine are really green this year , mine are under blue netting .
Here is a pic .
By the way ... thats not a rat behind the onions ... Its Jessie my Yorkie 

Those are impressive nets Dave Mac, but is that royal blue the only colour you could get hold of?  I'd have thought that given your persuasion in footie terms, you'd rather have brassicas riddled with caterpillars and eaten by birds than nets like that?