The pubco, which owns the lease on the building, has been battling campaigners since February over its plans due to concern about it remaining an LGBT venue.
A spokesperson for Ruth & Robinson said it had put a lot of energy into the project and it "believed we could create something very special" but for unspecified reasons claimed the plans "may not become a reality for us" - and that they believed it was "unlikely" another investor would come forward.
The spokesperson said: "In the absence of our involvement, the building may well remain empty. While this would be incredibly disappointing for us, there are significant opportunities elsewhere, where we will need to focus our energy and investment.”
According to the Camden planning website - the plans by Ruth and Robinson have been registered, but not rejected. Numerous discussions with campaigners have taken place in the last few months - and various celebrities have come forward to support the cause.
But Ruth and Robinson claimed the objections were not justified - and the plans presented to campaigners reflected the former venue's history.
The spokesperson said: “This venture would have been inclusive to the whole community and maintained a pub in the centre of Camden's High Street. In addition, we presented what we believed was an offer that was sympathetic to the history of the Black Cap, celebrating past performers and continuing the tradition of cabaret while providing significant new employment in the area."
Ruth and Robinson claimed the Black Cap requires significant investment and were "very keen to be the ones to provide that".
The pub company explained its plans had been to create a pub on three floors which would secure the use of the building as a pub in the long term and allow it to offer meeting facilities to the community for free, ensuring it “gave something back to local charities and interest groups”.
Last month (June), supporters formed the Black Cap Foundation group to progress the campaign to get the popular pub reopened as an LGBT+ venue.
Following this, the Black Cap Foundation wrote an open letter to the shareholders of Ruth & Robinson, which has a 25-year lease on the venue.
Campaigners and the pub company were at loggerheads in February this year after Ruth & Robinson took on the lease, with campaigners concerned that the operators were not going to reopen the pub as an LGBT venue or keep the Black Cap name.
Following the company's latest statement, programme director of the Black Cap Foundation Chris Clark said they were still running their Saturday afternoon vigils, which continued to be successful.
Clark also explained that the Black Cap team are confident there will be a favourable result for them at some point, especially following the success of the Carlton Tavern pub appeal which resulted in Westminster City Council winning its battle to have the iconic pub rebuilt ‘brick by brick’.
Said Clark: “This we believe considerably improves the strength of the ACV we have on the Black Cap.”
Just a week before its closure the pub, one of London's most well known LGBT venues since the mid-1960s, was awarded asset of community value (ACV) status by Camden Council.
Following its closure, a petition was set up by Camden Labour councillor Danny Beales to save the Black Cap, gaining 4,000 signatures in two days.
In the following month (May), protests took place outside the headquarters of pub owners Faucet Inns’ over the closure of the Black Cap and the potential closure of another venue in Haverstock Hill.