But Russell Goodway, reorganisation chairman for the Assembly of Welsh Counties which has campaigned hard against the creation of 21 new unitary authorities, said the co-operation did not mark an end to county opposition.
'We are getting together to oppose the Bill and will be putting down amendments which expose its many flaws', he said. The two sides also disagree markedly on the scope of a Welsh assembly - a subject not mentioned in the Bill but which they hope will be debated by peers at the first committee hearing on 17 January.
Geraint Price Thomas, under secretary at the Council of Welsh Districts, said an assembly would simply democratise the functions of the Welsh Office and the principality's 52 quangos. 'It must not take functions away from local government', he said.
'With a pattern of smaller authorities, it is the only possible way forward in order to get strategic planning right', said Mr Goodway. The associations' amendments reveal that a key area of common concern is a provision in the Bill which apparently allows the government to prevent new unitary authorities from trading among themselves.
Mr Price Thomas said the CWD's whole case for reorganising local government into a larger number of smaller authorities had rested on the premise that councils would be able to trade across boundaries. 'The freedom to trade in specialist resources will be a fundamental element in the reformed structure', he said.
Other amendments are aimed at abolishing what both sides view as the draconian powers of the Staff Commission - specifically its remit to consider and keep under review 'the organisation, management and remuneration of the staff' of the new authorities, and abolishing the requirement that councils seek the secretary of state's approval for decentralisation schemes.
The government hopes the committee stage will end on 27 January. It had earlier been suggested that debate might be limited to two days, rather than the three planned.