Two senior Conservative MPs vowed to defend the Cayman Islands' company ownership battle with the UK — while on a free trip to the Caribbean tax haven last month worth nearly £17,000.

Tory grandees Sir Graham Brady and Sir Michael Fallon travelled to the islands for five days at the end of June on a lavish junket paid for by the Cayman government.

The tax haven, along with other British overseas territories such as the British Virgin Islands, has been at the centre of a major transparency row over company rules which allow the superrich to conceal their assets behind shell corporations registered there. Transparency campaigners say these jurisdictions play a key role in facilitating corruption, money laundering, tax evasion, and other illicit financial activities.

Theresa May’s government had sought to force overseas territories to publish unprecedented levels of information about who owns companies in their jurisdictions, but delayed the attempted crackdown following opposition from places such as the Caymans.

Last year, the UK’s National Crime Agency warned that its efforts to combat money laundering on the islands were being frustrated by the Cayman government. "We can generally get from them clear, unambiguous beneficial-ownership information,” the agency’s director, Donald Toon, said in relation to overseas territories, “but we are having a difficulty with Cayman.”

The Cayman government is concerned that the new UK government, led by Boris Johnson, may impose more transparent beneficial-ownership registers on its overseas territories in order to make it harder for the ultimate controllers of offshore assets to keep their identities hidden.

On June 27, Brady, who until recently was chair of the powerful 1922 Committee of backbench Tories, and Fallon, the former defence secretary, flew to the territory in their roles as members of the All-Party Parliamentary Group for the Cayman Islands.