Health authorities struggling to adapt as primary care trusts take over their functions are working in the dark, in the absence of Department of Health guidance on criteria for mergers.
A slew of mergers and reconfigurations is expected to reduce drastically the number of English HAs over the next few years as increasing numbers of primary care groups move to PCT status.
But unlike in Wales, where HAs are to be abolished under the Welsh NHS plan, developments in England are being addressed at a local level with no national picture of their future role or configuration.
Unison health group national officer Roy Paterson said the union was 'advising a lot of senior managers in HAs about their own position'.
'It is a very uncertain time for people working in HAs. The DoH is not giving a clear steer.'
PCTs had been set up 'piecemeal', making it 'impossible to set up a clearing system' for displaced HA or PCG staff. 'At the most senior level, the solution has been to place supernumerary staff in regional offices.'
But Unison had told the DoH that there needed to be 'a managed and structured approach to retaining staff '.
'I do not think There is been a strategic approach, ' Mr Paterson said.
A senior NHS source told HSJ that reorganisation was being carried out 'quietly' so it did not look like a lack of concentration on service issues.
'Ministers are not that keen on mergers and things at the moment. Their priority is to get the waiting lists down, get cancer services in order. But we know we need structures to support that, so We are quietly having a look at it.
The two 'go hand in hand, but we have to look like We are moving on services'.
Just four HA mergers have been approved for 1 April. But 'discussions' are underway on a series of other reconfigurations and joint arrangements across the country.
In London, HAs are discussing plans that could result in a huge merger of four HAs into a single body covering the whole of west London. Another option would split west London on an innerouter basis.
A London region spokesperson said: 'Discussions are going on with all HA chief executives on the future layout of London's HAs.'
These would take into account the future organisation of social care as well as PCTs. But, outside west London, discussions were at a more 'tenuous' stage.
A North West region spokesperson said there were 'no specific plans' for mergers, although 'no doubt we'll have fewer and larger HAs' in future.
Project managers were doing 'preliminary work' on future structures in Greater Manchester and in Lancashire and south Cumbria, while two chief executives in the region now held joint appointments, running two HAs each.
A Trent region spokesperson said there were 'no plans at the moment' for HA mergers, despite having 23 PCTs up and running from April this year. 'There are several PCTs in each HA area, ' she said.
A DoH spokesperson said it had been 'considering criteria for HA mergers' and expected to offer 'short to medium-term guidance for the service soon'.
It was also working on 'the vision' for HAs' future. But it was 'too early' to 'say precisely when firm conclusions would be reached'.