Outside of the "homeland" UK-Scandinavia market, I do not think Norwegian have made any tangible head-way on short-haul. Their strategy seems to be based purely on having the cheapest price by far in internet search engines on routes like LGW-AGP, LGW-DBV etc and then they wonder why their yields are low in the UK market. It's nuts - they do not even seem to be tracking competitor pricing and pitching £x below it as they are quite often (from the web searches when I've been booking flights) way way below the competition.