As mentioned in an earlier reply, I would go for a BSA Light Pattern. Or a Meteor. Or a Lightning (the older type - plenty for sale s/h). My Light Pattern is built like a tank (it has survived for a long time), and it shoots well. Pretty light cocking effort. About 5 fpe in .177. So that's a tad lower than your request. But it will be absolutely fine for your father's use. Above that, it will hold its value, or even go up in value. I bought mine recently for 150 pounds, in excellent condition (restored, but I'm fine with that). My Meteor is nice too. I prefer the Lightning though. You will need a full length barrel on the Lightning to cock it easily, or a silencer fitted to a carbine barrel. My .22 Lightning has now got a .177 barrel, which reduced the power from about 10.5 fpe to 8.5 fpe. I prefer it in .177.
I find HW's to be heavy in comparison to the BSA's. The Light Pattern is really nice and light - what's in a name. Don't tell your father that it is also called the Ladies pattern. Being a modern man, that doesn't worry me too much.
Cheers, Louis