Simple answer.
When the last manufactured flu virus avian/bird flu was released the UK government brought about 50 million doses which weren't needed in the end. These millions of doses of tamiflu were all about to go past their sell / use by dates. then oops hey presto they got an excuse to flog them with another manufactured flu strain.
How lucky for the government and the manufacturer
I bet some of the MP's have shares! There's nothing like a bit of insider information is there? The same sort that Cherie Blair had 12 years ago when she bought shares in Pilkingtons glass and Hey Presto! two weeks later Pilkingtons K glass was the only one to be specified for all new double glazing!