The secret intelligence service, MI6, might be actively targeting bankers for 'operational officers' (AKA 'spies'), but it seems MI5 is also keen to hear from City applicants.
The difference, as you're no doubt aware, is that MI6 deals with international issues (hence Bond's adventures in exotic locales), whereas MI5 looks after intelligence issues on home soil.
It's currently recruiting for its annual intake of 'intelligence analysts.' Being an intelligence analyst is less exciting than being a spy, but it does seem well suited to people with an aptitude for mathematics.
As spokesperson for MI5 was reluctant to elaborate on their precise requirements, but according to the advert, they're looking for people who, 'bring experience of working with analytical and/or statistical packages and large electronic and hard copy data sets.'
According to one recruiter, this equates to quants, although not necessarily high-powered ones. "MI5 don't do much of the signal analysis work themselves. The more interesting quant roles are at GCHQ in Cheltenham," he says.
One stumbling block is the pay. Recruiters say GCHQ pay badly, and MI5 is offering 24-30k. After undertaking the notoriously gruelling interview and assessment process, you'll therefore be paid no more than your average civil servant.
Successful candidates will need to be able to get by on this amount. As an article in the FT recently suggested, financial services professionals are not always considered suitable for roles in the intelligence services as their high-spending ways make them more prone to being bribed.