I hope they mean that it will run oneway northbound, that is towards London Road rather than the other way. If it is the other way, you're bound to have a few drivers arriving at the one way section not having read the diversion signs. Smaller vehicles could go round Derby Hill when that isn't closed, or do a three-point. Anything big would have either to go the wrong way down the one way or reverse out.

I tried the email adddress on the works list to find out, but it wouldn't work for me.