JC, you're probably aware that BAE tried to develop Filton as a city airport in the mid 1990s. The application led to a planning enquiry following which the relevant government minister - I think Selwyn Gummer but humble apologies to him if I'm wrong - rejected the application.
Unsurprisingly, the application attracted numerous objections including one from the then owners of BRS, Bristol City Council. In the mid 1990s much of BRS's traffic was charter/inclusive tour and from their point of view a business airport across the city leaving them with mainly charter work was not something that they could contemplate with equanimity.
In fact, having one airport for scheduled business traffic, almost certainly turbo-prop/ small jet because the low-cost rush across the regionals had not yet begun, and another for holiday inclusive tours may not have worked either, given that the BRS catchment size is not the West Midlands, the North West or the South East.
When the celebrated wartime airport at Whitchurch was deemed too small for future development the city council opted for the former RAF Lulsgate Bottom (sounds vaguely Shakespearean) when legend/myth/possibly fact has it that they could have moved to Filton as tenants of the Bristol Aeroplane Company in 1957 when the council closed Whitchurch.
That's all in the past and realistically cannot be overcome now. As the Americans say, Lulsgate is now the only game in town and it's that or nothing.
It does seem the money people can see something in it because they've not been slow in investing scores of millions of pounds over the past decade and a half with much more in the pipeline.
I've been using the place as a passenger since the 1970s and I do admit to having a soft spot for it. I can't honestly recall ever having had a major problem there or been seriously discomfited in many hundreds of flights through it. I shall whisper it with the wooden desk gripped firmly but in all that time I've been diverted only once.