[SixSigma]

Also in the same piece

> Incredible as it may seem the prankster managed to obtain mobile numbers for both the head of the GCHQ surveillance centre and the prime minister by bluffing his way past both sets of switchboards.

So, we wonder, which is it ?

And, it also doesn't seem to me that incredible. Humans are the weak link.

> A government spokeswoman said a notice has gone out to all departments to be on the alert for hoax calls following the incident.

I presume, then, that normally hoax calls are not considered likely to occur - that is more incredible to me!