As for BA, one only has to look at how LH somehow operates long-haul out of 3 cities
The problem with a lot of wannabes and plane spotters is that they have no business acumen and can't navigate a balance sheet.....
Germany has a different demographic from the UK. The country is a Hell of a lot bigger and has a more spread out demographic. I am sure you selectively leave out KLM and Air France, Singapore, Swiss, Cathay Pacific etc who mainly operate from one core focus city. The UK is very heavily biased towards the South East of England and that gives London a massive advantage. BA has a massive investment in premium traffic and Executive Club beholden to a legacy cost base from it's nationalised days.
BA Manchester never made money with the BAC111. BA Manchester never made money with the B737-200s. BA Manchester never made money with the B737-500. Oddly enough, British Regional did quite well operating as BA, however when that firm was bought out for valuable Heathrow slots, the cost base went through the roof, the J41s were uneconomical from day one in the BA fold. It's a horrible fact of life in a large company. Add legacy BA Handling costs to the new nimble locos nibbling away your margins piece by piece and there is no way of stemming the flow of red ink.
The clue is the lack of stampeding Virgin and BMI flights desperate to fly long haul from the regions. As has been stated ad nauseum, the best long haul from the regions is run by those with a big old hub at the other end like Emirates and Continental.