Since 1 October 2014, when section 73 of the UK Patents Act was amended to allow for revocation to be initiated by the comptroller following a negative opinion on validity, a total of 13 opinions have issued where an examiner has concluded that a patent is either lacking in novelty or inventive step. This is out of a total of 42 requested opinions that reached a conclusion, 25 of which related to validity.
A first point worth noting is that these numbers are quite small, suggesting three possible reasons: i) people are reluctant to use the opinions service, possibly due to the public nature of the procedure; ii) the service is still not well known, even though it has been around for several year now; and iii) that there is just not very much contentious action around in the UK. I suspect the main reason is the first one, as many will be unwilling to put questions of validity or infringement before an examiner and have it decided on the papers alone, with the result being publicly available, even if the resulting opinion "shall not be not binding for any purpose" (section 74A(4)).
A second point worth noting is that the hit rate of a finding of invalidity, with 13 out of 25 opinions finding the patent to be invalid, is about 50%. If you are looking to use an opinion as a card to play in negotiations, this is not a bad hit rate. Sometimes, of course, a positive opinion can be useful too, particularly if the question is framed in the right way, as I know from personal experience relating to this one.
According to section 73(1A), the comptroller may revoke a patent if an opinion finds that section 1(1)(a) or (b) is not satisfied, i.e. if the claimed invention lacks novelty or an inventive step. He cannot, however, do so until any review under section 74B has been concluded, or once the three month period for requesting a review has passed.
It has now been nearly two years since the new procedure started, so how many patents have actually been revoked using section 73(1A)? Of the 13 negative opinions issued to date, only two have resulted in the patent in question being revoked (EP1837182 and GB2508152), although another one (EP2160936) should be revoked shortly, which I wrote about here [UPDATE 17 August 2016: it has now been revoked, confirmed by this letter from the IPO]. Three other opinions (relating to GB2493904, GB2487996 and EP2124945) resulted in the Office deciding to take no action, with no amendments being made to the patent, while for two others (EP1657072 and GB2503963), no action was taken following amendments being made. The remaining five (relating to GB2493904, GB2480275, EP0736030, EP1472164 and EP2018153) are currently awaiting a decision, four of these being within the 3 month review period, with the other one (GB2493904, which I have posted about before here) having been delayed due to arguments and extensions of time.
Although the overall count may change over the next few months once a few more decisions are made, the impression I get so far is that automatic revocation is likely to remain a rare option for the Office to take, and an option that is only taken when the case is very strong and/or if the patentee does not put up any fight. If the case for revocation is strong, a sensible patentee will be well advised to consider making amendments, either before the UK Office or, if applicable, centrally at the EPO. If the case is less strong, the advice would probably be to put up a fight to try to get the Office to back down, which they seem likely to do in most cases.