Thanks. Most probably it was, though unfortunately I could not see the rego'. It just seemed a bit coincidental that it was apparently flying a fixed pattern for a couple of hours and seemed to coincide with an increased presence of the 'security services' at BHX. I was stopped by them just returning a hire car. I suspected an 'incident' of some sort - like someone trying to smuggle an extra tube of toothpaste onto an aircraft maybe. I would have expected a survey aircraft to fly a moving pattern not to basically orbit on the same track for a couple of hours.
Thanks anyway.