I tried a search on Google, which came up with a few items, including the following:
"Viscount G-AOHI departed Glasgow at 14:22 GMT on a test flight which was to last about 15 minutes. The crew intended to carry out the flight in visual conditions. Weather conditions however, were marginal: rain and snow with 6km visibility, 8/8 clouds at 4000 feet and strong winds (50-60 knots) at 2000 feet. The plane had climbed to an altitude of 4000 feet when it crashed near the peak of Ben More mountain, 35 miles north of Glasgow.
PROBABLE CAUSE: "The pilot did not maintain a safe altitude and gave insufficient attention to navigation when flying VFR into an area of snow covered high ground in marginal weather conditions."
Have you tried obtaining a copy of the official accident report? I wonder why they chose VFR in such conditions? Doubt we'll ever know.