Filton was Bristol City Councils choice in the early to mid 50's to replace Whitchurch, though when Bristol Aeroplane Company were approached they refused on the grounds that you could not have a manufacturing and testing airfield operating in conjunction with a commercial airport, so that plan was scuppered.
Now had they gone another 12 miles to Weston super Mare airport with it's then miles of empty flat land around it and railway on the perimeter and M5 coming along later, who knows what we could have now in the southwest. Only one fly in the ointment with this idea- it was owned by the Bristol Aeroplane Company again and used for maintenance.
BTW just a point of interest, did you know that in 1936 W-S-M Airport was the busiest airport in the world this info supplied by a friend of mine and confirmed via internet