No.
It would be easy to get confused here, look in appendix D for more info on ancillary use. However, I think for this particular problem you need to look no further than a dictionary, which gives the explanation of "something of secondary importance"
The service risers are a necessary and accepted part of the residential purpose group. (They are of primary importance for the functionality of the place, just like the common corridors and staircases.) Storage cupboards would be of secondary importance, i.e. The flats could function perfectly well without them.
The service risers should obviously be fire protected, but the particular comments in B1 regarding ancillary areas and where they can open up onto, should not need to be applied.