And you were worried about the government holding data.
The likes of Google and Microsoft would not be trust worthy holders of any data, at the first request from the DoJ they would hand over UK data to the Murcan government, without qualm.
Then there are the competition and long term economic issues of doing this, government data is currently held by a whole host of IT vendors and government departments which provide jobs in the UK, I can't see this being the case here. It could only be a competition between Google and Microsoft to store your data somewhere in a cloud, without adequate audit or accountability. You may complain about the way in which government handles your data, but you try getting it out of a secure system, it only gets released by human error. Not by bad IT.
I would also love to see what CESG think of this idea, your health data is treated quite highly and aggregation rules make the whole database higher still. There is absolutely no way it would be in this kind of service, in fact if you think about it you could use all arguments against ID cards carrying this information against it being held by Google.
You should also ask yourselves why Google and Microsoft would want to do this, $$$$, not altruism, they think they can make lots of money out of controlling your personal data, and once they have control of it, they have the keys to who accesses it, and they probably won't give you back control, probably couldn't even if you wanted them too, because they will be the only game in town.
So think long and hard about this, this is probably a greater risk to your freedom and privacy than ever ID Cards are.