BertrandRussell do you think the problem with languages is that we don't start them young enough in the UK? From what I've read, children are far more receptive to new languages at a young age than they are in teenage years.
I'm just interested, I don't know the answer myself, but I have noticed that, over the years, pupils in my dcs' classes who come from bilingual families seem to have taken to the introduction of French in primary school much better than those that have never studied a language at all. I also have a feeling dd (6) would be very receptive learning a language at the moment, but it is no longer offered at her school and we are currently unable to afford private tuition. Unfortunately, dh and I aren't much help to her as neither of us are strong on MFL.
I accept your post did say, 'SEN apart', but there are a remarkable number of pupils that fall through the cracks in the SEN system or are considered 'not bad enough' for support/intervention. Surely those pupils need to be able to make individual, appropriate choices at GCSE, based on their aptitudes, abilities and potential to succeed, rather than a blanket policy? In fact, shouldn't pupils be encouraged to study what they are good at, so that they leave school with good qualifications that demonstrate their strengths, rather than all being funnelled through the same grinder. Education shouldn't be a one-size fits all process, by it's very nature it should be highly individual.
In our case, ds does have diagnosed SEN (although had we not fought he would have just been constantly been written off as 'not bad enough to need any help' regardless of how much he was struggling). His strengths lie in fact-based subjects/sciences/technology. Contrary to his primary school, who were the ones that claimed he had no SEN. He actually struggles with the semantics and complexities of communicating and understanding others using English, so taking on a new language on top is an awful lot to ask of him. We did try to give him a leg-up, so to speak, by paying for the additional French lessons/club in infants, but after three years he still couldn't string a sentence together, so we pulled him out. (Something he was very cross about, as the French teacher had a habit of rewarding effort with sweets. 
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