As a consultant albeit working for myself rather than a big 4 firm I recharge my clients for Y travel and book myself in Business or First depending upon the circumstances. I am amazed at how often major Financial Services Firms (typically big 5 Banks) cajole their staff into travelling with EZ et al in the mistaken belief that the fares are cheaper. The number of times I have encountered client staff forced to get up at 4am in the morning to travel with EZ to "save £50" when I know for a fact that net of the rebate, BA would have been £50+ cheaper than EZ (or £100+ cheaper than the headline fare for a short domestic flight).
The fact that the profit centres see no direct benefit from the corporate rebates, really shapes purchasing behaviour and this is surely not in the longer term better interests of BA? This type of behaviour goes right the way to the top. I know of at least one board director working for a Big 5 bank who went out of his way to fly VS in Y (as a "good corporate citizen"), despite the fact that BA J would have been cheaper and he was perfectly entitled to fly J.