Unpaid, not in contract lunch hour

[Aboveall]

Hello all.
my firm has decided to give us all an hours lunch break.
Now this in NOT in our contract and is unpaid.
So technically it still comes under govt law of the mandatory 20 mins I presume.

My question to yourselves is .....

I have been quite (apparently) reliably informed by our union representative that he virtually instantly said as its unpaid and not in my contract, I can take the hour when I want.

How say you guys?

[PallasAthena]

I am sure that isn't correct, you can't just decide that you are going to walk off the job and take your lunch break whenever you feel like it just because the break is unpaid. Your employer is entitled to tell you when in the working day you can take your break.