Difficult question to answer - you need a specialist in EU vs UK law.
In theory EU law is superior, and the same situation exists as for federal vs state law in the US. But perhaps it depends on whether these are EU advisories or EU law. I get the feeling that if an EU country wants to restrict something more than the EU statute, then that is OK - but they can't restrict it less. In other words if ecigs become a pharmaceutical in the UK, then if the EU class ecigs as tobacco, it would not be obligatory for the UK to remove the pharmaceutical classification - but that's just a guess.
However, current events seem to contradict that. I'm wondering if the MHRA was being forced to wait until the EU made a decision on this. However, the EU process has now been considerably delayed - their consultation does not end until December now, which means nothing will be done about this till spring 2011 at the earliest.
If this is the case, what MHRA might do is announce a waiting period of 6 or 12 months, for them to 'accumulate more data' or some such. If they do this, it shows they are waiting for the EU decision (ie, are being forced to wait for the EU decision by their masters). In that case the EU decision will be very important to us.
Whatever has caused the MHRA to delay their decision is obviously a serious matter. In my view they had already decided to make ecigs a pharmaceutical when they started the consultation process; that was simply a cosmetic exercise required by regulations. The decision had already been made by that point. As they have not given their 'decision' by now, it shows that they've been told to hold off. Since it appears that they have also not been told to dump the whole idea, it appears they are waiting for something. My guess would be the EU decision. Since that has been delayed by several months it suggests that the MHRA will soon announce a 'waiting period' or similar.
The situation in the US is much clearer, ecigs have to be either a pharmaceutical or a tobacco product, no other option is available. As it appears that the FDA have failed in their bid to make ecigs a pharmaceutical, they will become a tobacco product.