The person who told me that Stansted was less attractive than Gatwick for Long Haul ironically works for Norwegian!

It's not all about costs it's about yield and Norwegian would lose traction in the market from an outbound UK perspective as like it or not, a large % of London and SE based travellers who just won't make the trek to STN.
Their long haul strategy was to attack the market by very aggressively building market share in long haul out of London on certain core and under-served US routes. This would mean taking on BA on their home turf in London and under cutting their fares to build serious market share. In reality this means trading at a loss for some substantial period of time as IAG have deep pockets, so they either eventually get a win at Gatwick and fares rise to sustainable levels with losses falling over time, or they surrender the key point of their strategy due to unsustainable losses, which was to be a major player in this UK long haul market. In daz211's scenario, they get a "much cheapness" deal from MAG, move to another airport, and worst of all, leaving behind a lot of the new travellers they have brought to market, to remain at Gatters with BA. It's *really* difficult to shrink to sustainable levels of profitability, and leaving for STN would not take them forward in building market share and critical mass on which they've bankrolled the whole business plan. It's far from as simple as just paying less for the facilities, it's important but there are other factors in play.
And please don't leap all over me (again) for having an anti-Stansted agenda, I used it quite often and it does fine for me, so please no corbynista-style pile in. However in this case, it's not the answer to the business problems being encountered by DI around their Gatwick operations. Perhaps if they had stayed at STN all along and gone "big on a smaller more measured scale", then things might be different, but they stuck a finger in BA's eyes at their second biggest base.

I accept that STN can offer different customers to LGW, but there is a danger that they could just dilute yield. Why not consolidate at LGW, compete on underserved routes from Europe like Austin, Las Vegas and Seattle, using the short-haul network you already have and shuttling holidaymakers to Florida? Why launch a new base to slug it out on LON-NYC with BA(et al) and VS(et al). LON-MIA/NYC/BOS, for example, are available throughout 2019 for £279, return including taxes and meals (but not bags). More capacity between London and large US cities doesn't seem like a great way to do anything expect set fire to cash.

Wrong on the fundamentals here. All you'd do is dilute and cannibalsie your existing LGW operations. DI aren't going to serve both SFO and OAK from London for example, they're moving ops out of OAK to SFO, in much the same way they did from STN to LGW, as their analysis shows the latter airport is the more attractive option in market.
I think we're conflating short haul thinking with long haul.
EZY can serve AMS from LTN/STN/SEN/LGW easily, as that's something short haul point to point can support, four bases in London serving a mass market popular city destination. Also Jet2 coming into London short haul, capturing some ex MON and building out their own space. No one does this in long haul except the ever exceptional Emirates. Norwegian's issue of too many seats in the London market being sold below cost is not helped by adding more seats into that same London market, at another base, at *lower* costs.
You're attaching the short haul business model and assuming it'll work in that transatlantic and long haul market IMHO.

Emirates, is a different best in almost every way to Norwegian. Emirates is very similar in concept to KLM, for example, serving many surprising markets by augmenting O&D demand with a huge number of connection possibilities. Of course Fokker 70's and E-190's aren't as glamorous as A380's! Does a 777-300 load of people want to fly from Newcastle to Duabi everyday? No. But enough want to go to Middle East, Africa, Asia and Australia/NZ to make it work.

All I can say really is that quite a number of contributors seem to be looking through rose tinted glasses. A sense of realism needs to prevail.

What on earth could you mean c3b?

… & a reasoning for the short haul cuts & put forward above are efforts to bolster the long haul arm & that`s where we came in.