The 0.19 was on the pellet feeder – I’ve read conflicting things about scaling down pellet/method feeder hooklength diameters in winter, but in my view if a fish is willing to approach a method or pellet feeder then the difference between 0.19 and 0.15 isn’t going to be a deal breaker and I’d rather have the added durability on my side.
Since that match I’ve bought some Guru LWG hooks and made-up some 18 inch hooklengths on 0.13 N-Gauge – when fishing a traditional feeder I do think line diameter makes a difference and as there is more stretch in 18 inches of line (compared to 10cm) I’m happy to scale down.