Simon Calder: So, what will the British Airways merger mean for passengers?

While the benefits for shareholders of the BA merger deal are clear from the way that both airlines' valuations have soared, the advantages for passengers are more opaque.

The deal could facilitate travel to alluring Spanish destinations such as San Sebastián, but in practice British travellers to that fine city will continue to fly non-stop on easyJet to Bilbao or Ryanair to Biarritz, and making a short onward road journey, rather than taking a connecting flight via Barcelona or Madrid. And while more destinations in Latin America will be available to British travellers on a single airline, booking a flight from the UK to, say, Uruguay with a connection in Madrid is not an onerous task for anyone with an internet connection and a pulse.

BA and Iberia will collaborate closely on schedules, which could mean quicker connections in Madrid, but conversely BA's few remaining London-Latin America links could be axed to concentrate traffic on Madrid.

For years it has been clear that airlines have to consolidate to make sensible profits. With Air France effectively taking over KLM, and Lufthansa swallowing up several smaller airlines, the only two uncommitted big carriers in Europe were BA and Iberia. So, this is a marriage of convenience – or a forced marriage, depending on your perspective.

In other European air hubs, the national carrier has more dominance than does BA at Heathrow, which would have some 44 per cent of slots. Typically the "home team" – such as Air France in Paris and Lufthansa in Frankfurt – has 60 per cent, roughly what Iberia will have at Madrid.

It may be called a "merger of equals" but BA, with 55 per cent of the equity, appears more equal than Iberia. Mr Walsh will head the combined operation and his respected chief financial officer, Keith Williams, takes over as chief executive of BA.

While some BA managers doubtless face a regular commute to Madrid, the fact that the combined airline's commercial and operational hub is London will not be lost on concerned Iberia staff.

A worry is that BA's premium service may sink to Iberia's levels of customer care, in economy class at least. The Spanish airline's inflight service (no-frills in Europe, mediocre long-haul) is not something from which BA needs to take any lessons.

The merger could help solve the capacity problems at Heathrow. BA has long warned that failing to add another runway and a sixth terminal at Heathrow will drive passengers abroad; now, Mr Walsh has the chance to manage – and profit from – that process.