It enables information sharing between relevant staff in different departments, helping them to manage child protection more effectively.
The system has been operational for almost three months and IT staff are working on developing it from sharing generic information to being more tailored around individual cases.
Westminster City Council CIO David Wilde said the most important element of the system is that it helps people to work together.
"There are elements of what Contactpoint was looking to do but it works at a local level. We do a lot of co-working. Health and social care staff work in the same teams. It is not really a technology issue but about the people involved working together," he said.
"One of the problems for IT is just how much in the past we have seen it as the solution. But what is really needed is structural change as an enabler."
Wilde said one potential problem with Westminster's approach arises when children move around the country. But the answer lies not with more technology, but a better commitment to communication, interoperability and common standards between systems as big projects get cancelled.
"Interoperability is right back on the agenda. Data standards and information sharing protocols are back, and this time round we are going to have to get them right", he said.
"The standards that suppliers and projects use will have to be the same, so we do not end up with 500 housing benefits systems that cannot talk to each other."
This, he added, might require compromise from organisations. "Organisations will have to accept that the standards are right - you do not need an IT system that is 100% bespoke to your organisation."
Wilde said the public sector is likely to see an end to investment projects that do not have obvious savings.
"With Contactpoint, for example, there was a business case about the need to exchange information but there wasn't anything there that said what efficiencies it would achieve. Our business case shows how we can reduce the amount of menial work and duplication of information, and that was cashable."
• David Wilde is speaking at the SmartGov Live conference this week on the challenges facing public sector IT.