It wasn't transiting or strayed there, both aircraft were approaching to land at Cov, quote below is AAIB press statement.
19 August 2008
PRESS STATEMENT
Mid-air collision involving a Cessna 402C aircraft
and a Rand KR-2 aircraft near Coventry Airport on 17 August 2008
On 17 August 2008, at approximately 1138 hrs local time, a twin-engine Cessna 402C
aircraft and a single-engine Rand KR-2 aircraft were involved in a mid-air collision near
Coombe Abbey in Warwickshire. The four occupants of the Cessna 402C and the pilot
of the Rand KR-2 were fatally injured. Both aircraft were approaching to land at
Coventry Airport at the time of the collision.
The Air Accidents Investigation Branch were notified of the accident at 1205 hrs and
accident investigators were on site later the same day to examine the wreckage of both
aircraft and to commence a field investigation examining all aspects of both aircraft
operation.
The wreckage from both aircraft will be recovered to the AAIB’s facility at Farnborough
for more detailed examination.
An AAIB Field investigation is now underway and an accident report will be released in
due course.