I haven't found it to be so cold over the past few years to warrant using warm trousers a lot, just a couple of times in the day and a few more at night in my case. Our winters these days, in the South anyway, are positively balmy to how cold it used to be, for example in the 60s. When was the last time I saw a foot long icicle, I'm sure it was around 30 years ago?
Anyway I have solved my cold legs problem, easily and cheaply. I bought a pair of Decathlon warm leggings for £8.99, they look like jogging bottoms but are not elasticated at the foot end. For me they are perfect, very lightweight, cosy, comfortable and I can just wear under my normal hiking trousers trousers in the day, or I can use them as leggings to keep me warm at night. I'll be taking them with me to the April Borrowdale meet, just in case I get cold at night.