A double in HMRC requests for assistance from foreign governments has been seen in the past 5 years. This is in a conscious effort to combat tax evasion and collect unpaid tax from offshore accounts.
The Panama Papers scandal is thought to have applied extra pressure on to the HMRC to uncover and pursue evaded tax. The Panama case involved the exposure of leaked data from a law firm in the Central American republic. The leaked data uncovered the tax evasion of many wealthy UK citizens.