Solihull's ruling Conservatives have removed a major barrier to the founding of a new combined authority for the West Midlands by signalling plans to sign up.

It follows the decision by Coventry's ruling Labour group to also take part and means all seven major metropolitan authorities are prepared to join forces in a bid to secure billions of pounds worth of powers from government.

The move opens the door to establishing an authority across a region of almost four million people, overseeing issues like skills, infrastructure and regeneration.

But there are still tensions and a number of difficulties need to be settled – including the name of the new body and whether or not it takes the Government's maximum devolution offer by accepting a Boris Johnson-style region-wide metro mayor.

There could also be conflict over housing policy between the densely populated urban areas and those with green belt.

Solihull Council leader Bob Sleigh said he had come to the conclusion it would be better for the borough to be a part of the authority.

Coun Sleigh said: "It also comes from an understanding that in order to achieve Solihull's wider ambition for sustainable economic growth the borough needs a high performing regional platform of a scale and geography that attracts the significant inward investment needed to satisfy that ambition.

"I am convinced that an ‘economic plus' model, which includes skills and infrastructure, requires regional devolution at the right scale.

"I remain clear on the areas which need further discussion, they lie around, economic growth and how it's delivered, how we develop a skilled workforce to support the creation of jobs, business support by way of readily available advice and support and transport interconnectivity across the region.

"This will be underpinned by a single investment vehicle whose purpose will be to attract public and private finance to target the places were economic growth can best be delivered."

The vision for the combined authority is to operate over three local enterprise partnership areas – Greater Birmingham, Coventry and Warwickshire and the Black Country – which is by a distance the largest conurbation outside Greater London.

However, while the Post understands lots of surrounding districts in Warwickshire and Staffordshire have shown an interest in taking part, there are several hurdles still to jump.

A combined authority would signal to government that the West Midlands is ready to take on extra powers and funds from Whitehall departments.

The councils also recognise that combining strategic services such as economic regeneration, transport and trading standards, as well as back office functions, can make a significant contribution to their austerity budget savings.

Earlier this week Coventry's ruling Labour group indicated its intention to join.

Coventry leader Ann Lucas said: "I think that councils across the West Midlands working together to make decisions about major investment in things like transport can make much better decisions for Coventry than government officials in London can."

She stressed this is about moving power from London to the Midlands, not from Coventry to Birmingham.

"The new Government and the new Secretary of State are clear that devolution is a priority. If we're not part of a combined authority we won't get the extra funding we need to continue to develop the economic growth and success we've delivered locally over the past few years."

Talks between the Labour-run councils of Birmingham, Sandwell, Dudley, Walsall and Wolverhampton are well advanced and they are hopeful of a deal within weeks.

And even a potential change of control in Walsall from Labour to the Tories is unlikely to affect their participation.

The Tories are currently in talks with Lib Dems, UKIP and independents over a deal to seize control.

Conservative leader Mike Bird, who has launched a bid for a swift return to the Walsall leader's office after losing control to Labour last August, has previously been reluctant to forge closer links with the neighbour in Birmingham.

However, he said: "There is some merit in it. One question I will be asking is what's in it for Walsall and the Black Country."

But a deal breaker for Coun Bird would be any suggestion of the combined authority being named Greater Birmingham or the Birmingham City Region.

Prime Minister David Cameron has this week also indicated that a metro mayor may not be key to the West Midlands securing greater devolution and funding.

During a visit to a Handsworth health centre, he said that he did not believe "one size fits all" when it comes to local government.