A decision by the Tate and National Galleries of Scotland to quietly resume links with the influential art patron Anthony d’Offay, a year on from allegations against him of sexual harassment, followed intensive lobbying of trustees, it is understood.

Both bodies suspended contact with d’Offay in January last year after it was revealed in the Observer that d’Offay faced allegations of sexual harassment and inappropriate behaviour from three women with whom he had worked.

The Tate and National Galleries of Scotland have shared a prestigious programme known as the Artist Rooms, which was created after d’Offay sold them much of his multimillion-pound collection 10 years ago.

Separately from the historical allegations against d’Offay, police are also investigating a complaint that he sent a woman malicious messages. D’Offay has consistently said that he is unaware of a police investigation and categorically denies all allegations against him.

The Tate and National Galleries said in a statement: “Over a year ago we were made aware of allegations against Anthony d’Offay. The trustees of Tate and NGS took appropriate time to consider these. We have not been informed of any formal police investigation and trustees have since resumed contact with him.”

On Saturday the Times reported that investigations had “produced no firm evidence” and that the institutions had resumed contact with d’Offay. All the galleries involved with the Artist Rooms project were said to have been informed of the move.

The Guardian has approached d’Offay for comment.

The resumption of links has taken many in the art world by surprise. Even after the decision to suspend links with d’Offay, some staff at the Tate were deeply uncomfortable that his name was still emblazoned on the side of Tate Modern’s Turbine Hall, and the institution faced severe pressure from activists such as the campaign group We Are Not Surprised, which called on the Tate to remove d’Offay from its programme.

The Guardian understands that the Tate’s trustees faced intensive lobbying not just from critics of d’Offay but also from his supporters. “You have to convey the degree to which this has just completely polarised people in the arts community,” said one high-ranking source at the institution.

It is understood that an impasse between d’Offay and the Tate was over by March last year and “a dialogue” was under way between both sides. This took the form of discussions between his long-term business partner, Marie-Louise Laband, and Tate director Maria Balshaw, who was supported by the trustees.

More groundwork appears to have been laid on 27 April when, according to filings to the UK’s Companies House registrar, d’Offay stepped down as both a director and a “person with significant control” at the Artist Rooms Foundation, the charity vehicle set up to work with the Tate and NGS on promoting the original Artist Rooms collection.

While the foundation currently has millions of pounds worth of additional art on loan to Tate – a freedom of information request revealed that it included a large amount of work by the French-American artist Louise Bourgeois – the Tate said these loans were subject to a contractual arrangement under which they were destined to become “gifts” in perpetuity.

D’Offay’s quiet departure from the Artist Rooms Foundation took place against the backdrop of the discussions between him and the Tate. A senior source there said: “He has acknowledged that because of this controversy the status quo can’t exist any more.”