From users of British English, I have noticed the pattern of adding "time" after a unit of time, as in:
He has class in 30 minutes time.
My initial impression as an American is that this is quite silly as the fact that we are talking about time is already implicit in the unit minutes, which can only be used to describe time. (Edit: Okay, they can also be used to describe latitude or longitude, or angles, but I find it hard to conceive of an example where it isn't already obvious whether we're talking about time or a location on a map even without adding 'time'.)
However, I wonder if saying "He has class in 30 minutes time" contains more information than, say "He has class in 30 minutes." Is there some bit of information encoded into the use of the word 'time' here?
My questions are these:
1) Does the use of the word 'time' in this sense add additional information, or would removing 'time' from any sentence (when used in that way) not alter the meaning?
2) Is this slang? Is this formal English?
3) Are there cases where it wouldn't be OK to say "X [units] time", but it would instead be correct to say "X [units]", in British English?