Mr Masari has run an extremely effective human rights organisation known as the Committee for the Defence of Legitimate Rights (CDLR) which operates from Willesden, in north-west London.
The group concentrates its energies (and funds) on faxing dissident material into Saudi Arabia, including a weekly newsletter which claims a readership of 300,000.
Freephone numbers - which leave no trace on Saudi phone bills - mean that monthly telephone bills can be as much as pounds 27,000. The faxed newsletters include highlights from the British press about the goings-on of Saudi royals. There is even a "Prince of the Month" column.
Mr Masari has also publicised studies of corruption among Saudi princes in state organisations, including a recent study on the prospective privatisation of Saudia, the national airline.
"The CDLR has certainly had an impact in letting people know what is really happening," said Said Aburish, the author of a book on Saudi Arabia.
The high-profile activities of the CDLR - unstoppable, in the communications age - enrages the Saudi regime.
But the British Government was indignant, too, when Mr Masari appeared to condone the bombing in Saudi Arabia in November of a building used by United States forces.
Mr Masari himself later insisted that his words had been taken out of context.
He claimed he did not himself see the US forces as a "legitimate target", but only believed that this was "the perception of the common man" in Saudi Arabia. That may sound like a fine distinction. And yet, Mr Masari's own newsletter, responding to the news of the bombing, appeared less ambiguous.
"Despite the fact that the CDLR is opposed to violence. [It] indicated in many bulletins that what happened is a natural end result of the complete lack of freedom of speech and assembly, and oppression of reformers," the newsletter said.Reuse content