Just for the record, if
anyone has a set of decent knives - then NEVER use an electric sharpener or any rotary, gadgety or gimmicky sharpening tool !!
Hi
Mooria have you considered getting him a
diamond steel?. I have one of these and it brings my (Henckels) knives up a treat.
If any of your Dad's knives are quite old and don't respond that well to sharpening with a steel, then it may be time for them to be 're-ground'. I don't know where you could get this done in Northampton these days (there used to be a little place near Kettering many, many years ago!)
In looking for the other link, I did however come across
this - but I haven't tried it myself. (I have had my Henckel's for years though!)