I cut last year's old leaves off before the new flowers open just so you can see them. Then new leaves start growing March.

Remember that it is only on H. orientalis and its hybrids which have all the old foliage cut away. The others only have dead or dying or diseased foliage removed.

I think I went wrong in the Autumn by cutting large and unsightly leaves off to tidy them up a bit.

In our previous garden where we had hundreds of them I used to begin cutting back in November as it took me until the end of February to get them all done. Only ever lost a few to the Hellebore bacteria/fungus if I missed cutting them back. When I cut them had no effect that I could see on survival.

that is a good point Owd, re the species. I just assumed the hybrid ones.

I cut off dried up/ dead leaves when I see them, and also live ones when they stop me seeing the flowers, rightly or wrongly, but it's a huge old plant, i'll do a pic when it flowers next, think it's a Lenten rose tho.