"It is pretty ironic, given what has happened recently," said Clarkson yesterday.
"For one thing, it calls into question the efficiency of the vetting procedure and, for another, it makes you wonder why the Security Services are not doing this stuff themselves from their own resources. But they're not likely to admit it, are they? ... They just never admit things like this.
"I'm not in the least surprised to hear that Coulson would be vetted by a private individual, but I suspect most people assume the Security Services do their own donkey work, although they, like everyone else, are suffering from the current splurge of cuts."
Questions have been raised as to why Coulson was not submitted for "Developed Vetting", the highest form of clearance, as soon as he started working in Downing St.
There was speculation this was the result of royal or Civil Service pressure, or that something might be unearthed that would prevent him being awarded clearance.
Coulson underwent a total of three vetting procedures during his time working for Cameron, yet it seems none uncovered serious concerns about the extent of phone hacking during his time as editor of NOTW (2003-07).
The final stage, unusually for someone of Coulson's closeness to the Prime Minister, did not begin until six months after the election.
The Developed Vetting process, which could take up to six months, was cut short by the media chief's resignation in January.
- INDEPENDENT