I"ve seen the Canadian version of the 24 hour ration, which I'm guessing is based on the UK one. About 7"x5"x5", like four cans, a little on with crackers?, some little packets of verious stuff, and an accessory pack? It was mid-80s vintage, in an army/navy store, about 6 years ago *shudders*. That's about the same size as a day's worth of MREs, maybe a little smaller, just shaped differently.

The tablets taste like malted milk balls, as others have said, becuase I think that is what they are, just doped with atiny bit of fiber and nutrients. I've never bought into the whole "developed by special forces" gag. Maybe by a couple of operators, or former operators, but not officially, at least not as a meal replacement. They are "Commando Candy".