Well I had a quick chat with out head of customer relation on this who worked for an airline for many years. In essence MCT is defined by your “On stand” time. So when airlines put there schedule together it is called Block to Block time which is basically what Canucklad has mentioned. Some airlines apparently take there on time performance figures by landing times – but not on stand times which as we know can be very different.
With regards to responsibility for MCT once the plane is “On Stand” – not doors open – then the airport is responsible for the throughput of people – not the airline. So if doors don’t open for what could be a myriad of reasons this is not the airlines fault – but the airports. So if a passenger then misses a connection – they don’t have to re-protect you (though any airline worth their salt would). I was told this is why you should take insurance which includes Missed Connection / Departure – as airlines may say this is an insurance issue.
So I think this is the official position that I have been able to establish. Gives a second question that if an airline (via what the airport allows as minimum connection time) doesn’t help then could a passenger make a claim against the airport?