Ofsted has run the scheme for a number of years as part of efforts to boost the number of inspectors at its disposal and improve the quality of inspections.
However, in 2015 the inspectorate's social care director Eleanor Schooling conceded that the scheme had enjoyed little success due to the fact that staff needed to commit either one or two years to the programme and required 18 weeks of training before becoming a properly authorised inspector.
As a result, the requirements were relaxed, so frontline staff who wanted to assist with just one or two inspections could take part.
But Ofsted has now confirmed that the scheme has been "phased out" and closed to new recruits, but could be reopened in the future.
An Ofsted spokesman said: "Ofsted already has 14 social care inspectors who are serving practitioners in local authorities.
"We are not recruiting more at the moment as we have enough inspectors. The scheme is working very successfully and these inspectors bring significant experience. We will recruit more if and when they are required."
In 2016 Schooling told CYP Now that involving professionals in this way gives a "much richer" inspection and Ofsted had hoped to have a "handful" of part-time seconded inspectors available in each region.
Seconded inspectors had the choice of becoming a full-time inspector for one or two years or given the option to be part-time and complete three inspections over an 18-month period. All seconded inspectors were offered free training and ongoing professional development by Ofsted.
