Heard a story about this accident from an ex Radar Type 82 fitter who was working at Watton at the time. Both aircraft were under the control of Eastern Radar at the time of collision. As stated controllers at Watton lost radar contact on both aircraft due to heavy rain clutter on their scopes. One result of the accident was the fitting of a circular polariser on the transmitter aerial of the Radar Type 82 to reduce the effects of rain clutter.