Lord Ashcroft, one of the Conservative party’s biggest donors, faces fresh questions over his offshore affairs after the Paradise Papers revealed a previously unknown trust sheltering his vast overseas wealth.Scores of emails and financial statements chart the inner workings of the Bermuda-based Punta Gorda Trust from its creation in 2000, just after he became a peer.

The documents run until 2016, when the offshore law firm Appleby, which acted as trustee, terminated the relationship, a decision questioned at the time by Ashcroft’s representatives.

The value of the trust fluctuated, but a leaked financial statement recorded it as having assets of $450.4m (£341m) in 2006.

Several emails show concern being expressed by Appleby, the firm at the centre of the Paradise Papers, about the way the trust was being run. The concern was that Appleby, as trustee, was in effect being asked to rubber-stamp decisions it believed it should have been informed about in advance.

n an email in 2010, a senior lawyer for Appleby wrote: “There have been very large sums of money involved and I am very concerned that there has been inadequate supervision of both transactions and distributions … To put it bluntly, we seem to be told nothing, whereas we carry the responsibility of acting as trustee.”

There is nothing illegal about the trust, but its existence could prove awkward for Theresa May. She faces having to square donations from Ashcroft with the Conservative pledge to bring transparency to the offshore industry. Labour is also calling for wide-ranging changes.

Ashcroft, 71, is a former party treasurer and deputy chairman who has given millions to the Conservatives, including £500,000 towards the party’s most recent campaign. The pro-Brexit peer is influential in British politics through his polling company and the website ConservativeHome, a centre-right blog aimed at grassroots party activists.

Ashcroft is also one of the largest individual donors in Australian political history, with gifts to the Liberal party including a single donation of A$1m in November 2005.

Ashcroft’s spokesman, Alan Kilkenny, said the peer had never engaged in tax evasion, abusive tax avoidance or tax avoidance using artificial structures, and “any suggestion or implication that he has will be vigorously challenged”.

Kilkenny declined to pass a series of questions from the Guardian to Ashcroft, dismissing them as “scraps of information, which do not amount to evidence, gained from stolen documents. Lord Ashcroft would not read such a communication and there is no point in attempting by other means to communicate with him.”

George Turner, a spokesman for the Tax Justice Network, which campaigns for reform of the offshore industry, said: “The idea of a trust is that a person gives up their property to a trusted person to manage for the benefit of a third person: a family member, say, or a charity. The fact that the original owner of an asset gives it away and technically no longer owns it can have tax ‘advantages’.”

As a high-profile Tory supporter for more than 20 years, and a man whose businesses have been based in tax havens, Ashcroft remains one of the most divisive figures in British politics.

He was turned down for a peerage in 1999 and 2000 because he was a tax exile in Belize. He gained his title after saying he would take up permanent residence in the UK again.

There was a political storm in 2010 when he confirmed he was still a “non-dom”and did not pay tax in the UK on his earnings abroad. Ashcroft then promised that he would abandon his non-domiciled status to comply with a change of law in 2010 introducing curbs on such individuals sitting in parliament. Ashcroft remained in the Lords until 2015, when he resigned his seat but retained his peerage.

The Punta Gorda Trust was set up in April 2000 when he was a “non-dom”, with his three children named as beneficiaries. Ashcroft was named as the settlor and a beneficiary, the only one entitled to income for life.

The trust became the focal point for a series of multimillion-pound capital distributions, loans and share transactions. Typical of trust activity is a document in March 2002 saying the trustees agreed to forgive a loan of $29.5m to Ashcroft.

The original trustee was the Reid Trust Company, which was taken over by Appleby Services (Bermuda) Ltd.

Concern about the running of the trust emerged within six months of it being set up. Reid warned an Ashcroft adviser: “I would like to emphasise at this point that it is imperative at all times that the trustees are aware of any and all transactions to be entered into prior to transactions occurring.

“To do otherwise will only serve to undermine the integrity of the trust as the trustees are being advised of actions taken in connection with trust assets, which should be under their control, after the event.”

Ashcroft appears to have taken this on board, with the trustee considering and agreeing to various requests.

In a review of the trust in 2009, Appleby expressed further concerns. “My analysis of the final last July indicated that there are very significant payments being made from time to time and we must ensure that these are properly considered and recorded by the trustees,” it said.

Although the children were named as beneficiaries, they seem to have been unaware of this. Minutes of an Appleby meeting in 2010 state that one of Ashcroft’s advisers had “indicated that the settlor’s wife and children were not aware of the existence of the trust”.

The children were replaced in 2010 as beneficiaries by the Cayo Foundation, which distributes money to charities linked to medical research, the military, fighting crime, education, the arts and young people.

The subject of tax surfaces in several of the emails and documents. Appleby drew attention to a law change by the Labour government in 2008 that could have had tax implications if any of the trust beneficiaries were resident in the UK.

The decision of Appleby Services (Bermuda) Ltd to end the relationship with Ashcroft was taken at a 2016 meeting in Hamilton, Bermuda.

Appleby declined to comment about Ashcroft. But in a statement published on 24 October, in response to a series of allegations about this matter and others, the company said it had “thoroughly and vigorously investigated the allegations and we are satisfied that there is no evidence of any wrongdoing, either on the part of ourselves or our clients”.

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