Hi,
How on earth do I get the front wiper blades off a Croma?

I worked it out. Take the wiper arm away from the windscreen. Rotate the blade clockwise as far as it will go. You can now push the blade towards the windscreen, removing it from the arm. A bar/pin attached to the arm goes into a hole in the blade.

Yep, easy as soon as you've done it. I remember staring at mine the first time too - it looks impossible for them to come off.

It makes a pleasant change for a design to actually get improved - they're a million times better than the old hooked rod things.

Obviously not a Vauxhall part then Doofer ;-0