The trouble is that we have no way of knowing if this is just the security services stiring the pot or a real threat.
Since Blair, Bush and Co. have an interest in keeping us scared and therefore supportive of the "war on terror", and following the "WMD deployable in 45 minutes" statement, one has to ask is this real or a fake threat?
The trouble is that as with most security work, we can usually never know if there was a real threat that was deflected by our hardworking security services, or an imaginary threat dreamed up to justify bigger budgets.