It is - In case you misss the start on E4 and want to catch up. Also I suppose, because it provides channel four with an extra digital channel on a "use it or lose it basis" which at some point in the future they may use for something else, as in More4+1, which will be film four soon.
There are quite a few +1 programmes, which as said before can be quite handy if you have missed the beginning or even unable to watch something at the earlier time. I've often forgotten about a particular prog I would like to view and this certainly gives me a chance not to miss it completely. Put it down to a senior moment Lol
But surely there are legal issues too here with this channel (spelt right? i never know) as Big brother Live is say on E4 6pm - 7pm but on E4+1 the same show with the same title is on 7pm-8pm. How can it be called live? its an hour later, NOT live!