I use that road probably less than once a month, but I used it over the summer when the roadworks and speed reduction signs were being put in place so was aware of the change.
Agree having the 40 sign before the roundabout is crazy. Coming the other way from the A61 roundabout has been 40 for a stretch then up to NSL, the NSL has now been reduced to 40.
I'm sure I read the stretch between Lawnswood and Sainsbury's Moortown is to be reduced to 50 as some point.
Check the TRO to see when the new limit actually came into force,