This same practice is currently going on in the Scottish referendum and will re-occur if we ever get an In/Out EU referendum. Richard North, http://www.eureferendum.com/ , has picked up on this in his blog and his piece is well worth reading.
These businessmen are of course only interested in their profits and bonus. The easiest way for them to achieve this is to cut their labour costs and the easiest way to do that is to employ immigrant labour hence their oft repeated claims that immigration is good for the economy. Social housing costs, health care, education for immigrant's children are not on the business profit and loss account but they jolly well should be!
More puzzling is why the media and the BBC in particular give these self seeking money grubbing creeps so much air time. I opine it is because these big firms provide a nice little earner for these equally greedy media types. Its not just the adverts but its these nice little conferences, training days etc are all very lucrative for TV types and of course z list politicians but paid for by these businessmen's company shareholders.
Its never going to be possible to legislate for this abuse of our democratic process but at least it deserves some publicity from the media who are not in big business' back pocket.