Yeah I know. The picture is not representative.
I'd upload a pic of the bottle next to me now but now you know MC is on them am sure you'll know what to look for ;)
Good luck! Found them in Co-op & Tesco if that helps (never went to any Asda)
No, you need to look in other shops then.
There are 500ml and 1l bottles, both sizes with the offer.
To check it's part of the competition, check the label before you buy. The Master Chief on it is your clue.
However the drink indeed is not very popular 'normally'. But I've had three entries on...