UK had great laws geared towards mobile workforce and specialist contractors could claim business costs against their tax - this combined with little bureaucracy and use of de facto lingua franca was a recipe for success. From April next year this will end as government was looking for extra money and decided to adjust IR35 (a law that essentially says if you work as an employee you should be taxed as employee, but without having any employment rights), so that now the client has to determine whether contractor is a deemed employee or not. The problem is that the penalty for doing wrong determination only exist if you declare that someone is not a deemed employee, but investigating civil servant finds the opposite. That means risk averse companies change their contracts so that the contractor will always be deemed an employee to avoid getting fined (the fine plus all taxes that would have to be paid even if contractor already paid all the taxes). This still wouldn't be a problem if the rules about deemed employment were clear - but after so many years HMRC still keep losing cases where they get the determination wrong themselves. What this means for contractors? They essentially become employees without rights and the effective tax rate they will pay may be even around 54% plus they won't be able to deduct any business expenses (except what employee could have deducted - but that is essentially dead). Suddenly the market for IT specialists in the UK became unattractive and companies who are struggling to find people working for severe pay cut start to look overseas.

edit: if you want more spice to this, then imagine that our Chancellor is married to woman that her and her father have substantial stake in Infosys.