First impressions usually ring true and the ex-spook Mr David Shayler certainly looks like a confident man. Just as a former MI5 intelligence agent, Mr Peter Wright, before him found out, the security services get extremely jumpy when their prodigal sons fly the coup. But just as Mr Wright faced down the security services and published his Spycatcher expose of MI5 in Australia in 1987, Mr Shayler is also sticking to his guns.
His return to Britain this week, with an ironic photo opportunity against the backdrop of the White Cliffs of Dover en route, presents the British government and the security services with an interesting conundrum.
The former attorney general, Mr John Morris, granted permission to prosecute Mr Shayler in 1998. He was duly charged on Monday with two counts of breaking the Official Secrets Act, which banned him for life from talking about his MI5 work.
The charges relate to allegations Mr Shayler made in the Mail on Sunday newspaper in 1997, a few months after he left MI5 but before he fled to France. He claimed MI5 held files on prominent Labour politicians, including Mr Jack Straw and Mr Peter Mandelson, and musicians such as John Lennon, on the grounds that they were communist "subversives".
In the article Mr Shayler also pointed to "incompetence and bureaucracy" at the heart of MI5 over its surveillance of suspected Libyan intelligence officers working in London. The charges against him also relate to documents he allegedly removed from MI5's headquarters at Milbank.
From the moment Mr Shayler stepped onto British soil this week the whole case assumed an air of surrealism. He was not charged, as had been expected, in connection with his most serious and potentially damaging allegation that the foreign intelligence service, MI6, was involved in a plot to assassinate the Libyan leader, Col Muammar Gadafy, in 1996.
The omission raised serious questions. Was the MI6 allegation just "pure fantasy", as the Foreign Secretary, Mr Robin Cook, once suggested? Did the police have insufficient evidence to charge Mr Shayler? Or was it as he claimed this week, a signal that the government had "backed off" from a fight?
Mr Shayler will make his first appearance in connection with the case at Bow Street Magistrates' Court in London later today. And the government and the security services will be watching with mounting anxiety as he attempts to drive a horse and carriage through the Official Secrets Act.
The problem for officialdom is that while Mr Shayler does not deny that he has broken the law, he insists that a bad law, which denies him a public interest defence, as a citizen forced him into illegality.
The Labour government opposed the present form of the Official Secrets Act when the Conservatives introduced it in 1989, arguing unsuccessfully that a public interest defence should be included in the Act. Labour now watches and waits as Mr Shayler faces prosecution under the same Act.
As Mr Richard Norton-Taylor, security correspondent for The Guardian said recently, the securocracy is "in a quandary" over this case. The charges against Mr Shayler could be dropped at the last minute. But if the threat of legal action is lifted, it raises the possibility that he could continue making his allegations and the government could face serious embarrassment.
On the other hand if the trial goes ahead and Mr Shayler wins, the Official Secrets Act would be dead in the water and the government wouldn't be too keen on having to rewrite or repeal it in the run up to a General Election.
At Bow Street, Mr Shayler will mount his defence on the grounds that the European Convention on Human Rights, which will be introduced in England and Wales as the Human Rights Act on October 2nd, enshrines his right to freedom of expression and can be retrospectively applied.
Article 10 of the Convention, which has been incorporated into the Act, states that everyone has the right to freedom of expression - but that it can be restricted in the interests of national security to the extent necessary in a democratic society.
This case, if it takes place, will test the extent to which that test can be applied.
But Mr Norton-Taylor suggests the securocrats have thought up a "clever wheeze". Even though some government lawyers privately recognise that the Convention and the Official Secrets Act are incompatible - a point picked up by The Times - a trial judge could allow defence lawyers to make a public interest case. If that happened, the government would be able to argue that even though the Official Secrets Act does not allow a public interest defence, such a defence can nevertheless be made through judge-made case law.
There is a possibility, however, that Mr Shayler may not get his day in court. On November 20th, a former senior British Army officer, Col Nigel Wylde, is due to appear at the Old Bailey in London charged under the Official Secrets Act with allegedly passing information to a journalist, Mr Tony Geraghty. Mr Geraghty's 1998 book, The Irish War, described army surveillance systems in Northern Ireland.
If the case against Col Wylde founders on the freedom of expression test, it is unlikely that Mr Shayler will ever face prosecution.