Military veterans are missing out on vital care and support when they return to civvy street because the Government is failing to keep track of where they end up, council leaders have warned.
Millions of former servicemen and women are entitled to priority housing, school places for their children, jobs and health support but are falling through the cracks, according to the Local Government Association (LGA).
Every council in England has now signed up to community covenants pledging to support veterans, but without accurate information about where they are living the impact will be limited, it said.
The LGA called for Whitehall to share information about veterans for the whole of their lives to ensure they receive what they are entitled to.
Vice chairman Gary Porter said: "Councils are proud to stand shoulder to shoulder with our armed forces and are committed to help those serving our country on their return from duty or veterans already living within our communities.
"There are more than four million veterans in the UK and armed forces personnel have much to offer. However, some veterans struggle with the transition from military to civilian life, finding it hard to access the services they need. Financial and employment advice, housing or mental health support offered by local authorities across the country are proving invaluable in helping our brave servicemen and women.
"We fear millions are getting lost in the system and are missing out on vital support because they are unaware of the benefits available to them. Councils cannot help them if we don't know who they are and our efforts will be hampered unless we, as a nation, keep more accurate information on where they live.
"We recognise the need for privacy and data protection laws, but we think it's time for the Government and other bodies to work with us to find a way to share data that will ensure that funding, information and support follows our service personnel for the rest of their lives."
Under the covenants, veterans are offered priority access to affordable housing, training courses and priority school places for their children before they move to an area as well as debt advice, free gym access and bus fare discounts. Counselling for ex-forces personnel with mental health or physical problems is also available.
A Ministry of Defence spokesman said: "We are delighted that all local authorities in Great Britain have now signed a community covenant.
"But we recognise that the data on our Armed Forces community, particularly veterans, remains patchy. Progress is being made.
"The covenant partnership, the MoD, local authorities and their other local partners are working to pool information to the benefit of all.
"Hampshire County Council have provided an excellent example. They commissioned a survey into the numbers of Armed Forces community in their area which helps supplement the information already held by the MoD and other organisations such as the Royal British Legion."