The Scottish market was way too small and seasonal at the time, with four majors flying daily to the US and one to Canada, no one made money. And United and Air Canada could stay in market using British Midland rather than commit their own metal, it was the early days of STAR ALLIANCE. It rebalanced when Continental offered a daily year round GLA-EWR on the right size of aircraft for the time.
Cut to BAA selling EDI and later GLA and the market is a lot bigger and can support multiple daily operators BUT mainly from one hub airport.