A group of “accidental activist” families have succeeded in their efforts to secure the future of their children’s care home after uncovering serious alleged management failures that took the charity to the brink of bankruptcy.

The families launched a campaign after discovering that William Blake House, a residential learning disability care home charity in Northamptonshire, owed £1.5m in unpaid taxes, had paid its former chair £1m in fees, and was close to bankruptcy.

Their campaigning prompted a rare Charity Commission inquiry into alleged financial irregularities at the charity, helped underpin a detailed rescue plan, and outflanked potential takeover bids from private sector rivals.

Administrators confirmed the services will be run by Camphill MK Communities, a learning disability residential care charity that shares a common care ethos with William Blake House and has the backing of the families.

“We are overjoyed and so relieved to have learned today that this lovely charity is going to take over the care of our vulnerable children and provide them with a home for life,” the families said in a statement.

The administrators said that pending regulatory approval, the move signalled “a significant and positive step forward in securing a stable future for the residents staff and wider community connected to William Blake House”.

Funded mainly by local authorities, William Blake House is home to 22 adults with learning disabilities, autism and complex care needs who require support throughout the day and night. Many residents are non-verbal.

The families said: “Our months of determined effort to find out the truth, to confront the authorities and to be heard have finally paid off. Now that we have Camphill with their integrity and expertise, we can sleep at night.”

Camphill MK’s chief executive, Tim Davies, said: “This is about more than organisational change. It is a long-term commitment to people, to community and to the belief that people with learning disabilities deserve lives filled with meaning, security, friendship and belonging.”

The families’ victory is a rare good news story from a care sector in crisis as a result of shrinking care fees, staff shortages and rising wage costs. Several learning disability care providers have shut, merged or cut back on services in the past 18 months.

The story of a group of passionate, well-organised parents determined not to put up with sub-standard care for their disabled children has historical echoes. Many learning disability charities were set up the 1960s and 1970s by families appalled by the dismal services offered by state institutions.

The leader of the Liberal Democrats, Ed Davey, who highlighted the campaign in the Commons in March, praised the families: “As the father of a disabled son, the situation they have been put through is one of my worst nightmares, and I commend their courage in fighting for their loved ones to get the best possible care.”

The saga began in autumn when a handful of families realised that serious failings in the management, finances and governance of the charity threatened the future of its care services and put their childrens’ “home for life” in jeopardy.

Facing a race against time, they spent thousands of hours piecing together the charity’s complex finances and tangled interests, getting fellow families on board, interviewing former trustees and pleading with regulators to intervene.

For weeks the families waited to hear whether charity and care watchdogs would act. In February, acting on information from the families, the Charity Commission opened an inquiry into William Blake House’s finances over concerns the charity’s resources had been used for unauthorised personal benefit. The inquiry continues.

In March, the commission took over the running of the charity on an interim basis. The appointment of an interim manager over the heads of the existing board happens when the commission considers the consequences of not acting would be a major risk of harm to the charity’s finances, assets, services, beneficiaries or reputation.

The families lobbied to prevent the insolvency courts simply winding up the charity, before facing an anxious wait to discover who would take over the charity’s services.