The leader of Warwickshire County Council has vowed not to rush into full membership of the West Midlands Combined Authority – heeding a playful plea from her deputy to avoid a "soggy bottom".

Controversial plans for the county to become constituent members, which would lead to the region being covered by a directly elected mayor, are to be assessed by professionals at the county council after the cabinet gave the go-ahead for work to continue.

The West Midlands Combined Authority, currently led by Conservative mayor Andy Street, is a formal alliance of many councils across the Midlands from Shropshire to the west to Warwickshire to the east. 

The councils still function in their own right but in a move towards concentrated powers for regions of the country, the authority has a much greater say over how to bring in investment and allocate money to economic development, housing, skills and transport.

Seven councils – Birmingham, Wolverhampton, Coventry, Dudley, Sandwell, Solihull and Walsall – are constituent members with full voting rights.

Warwickshire and four of the five districts and boroughs in the county are among many non-constituent members that have less of a say and involvement and do not come under the mayor's remit. Warwick District Council is an "observer organisation" on the periphery with no voting rights.

The prospect of the county joining – and taking each borough and district with it – has caused an outcry, particularly from those who fear it could be a back-door way of creating a unitary authority for Warwickshire, a single council that covers all of the service areas currently split over two levels of local government. 

That was reflected in a softening of the language around the recommendation to cabinet, describing this as an "opportunity" for the council, something that had previously been described as an "option". 

Recognition that it would join "as a two-tier authority area" was also weaved in with the upcoming work now set to include "other options that may be available" as well as full membership.

Leader Cllr Izzi Seccombe struck a conciliatory tone in introducing the report, noting there had been "a lot of speculation and discussion" since the paper had gone live on the council's website last week.

"It is very much, in my view, a stage-by-stage process," she said.

"I think there are undoubtedly opportunities we should look at but there are also a number of challenges we need to consider. This piece of work looks at the opportunities and risks.

"Some of those risks will be around understanding challenges around transport and our budget around that, what it means for a large rural area and how that fits with the metropolitan boroughs that are already there.

"It also needs to think about the economy, skills, transport and highways, the strategic element of transport and the strategic housing element. 

"It is my understanding that there has been genuine benefit for certain parts of the combined authority like the Black Country where a lot of land remediation has been needed to move forward development that had looked unattractive to developers.

"All of that needs to be considered but there are some real challenges, not least being a two-tier authority, and the only two-tier authority. We definitely need to understand the governance, costs and voting arrangements to be undertaken.

"I know that is not simple. I think there are definitely people paid far higher than most of us in Whitehall (government departments) who are probably working on that but as yet, we have not seen the outcome of that.

"In order for us to make sure we make a decision based on evidence, we need that work done." 

And it was the ability for that work to be done – the council's review of how it will all work and a public consultation to inform the decision – ahead of the application deadline in October, set so Warwickshire residents can vote in the mayoral elections in May 2024 if this progresses, that caused concern across the political spectrum, including from Cllr Seccombe's right-hand man.

Cllr Peter Butlin, the county's deputy leader and portfolio holder for finance and property, admitted he had concluded "six months ago" that Warwickshire should join based on the direction of travel around funding for economy and transport and the prospect of missing out. 

"Michael Gove presented the possibility of going in on a very tight timescale and I concluded we could possibly do it," he said. 

"All of a sudden, as I looked at the nitty gritty of it, I thought it was a rush job. We have been pushing back at DLUHC (Department for Levelling Up, Housing & Communities) to extend the timescale.

"To put it another way, I think of it as baking a cake. If you don't take your time to get the right ingredients and the right timescales, you will end up with a soggy bottom and that is my one big fear. 

"I listen to all the arguments (from other parties) and funnily enough I agree with pretty well everyone. I am thankful for the contributions because everyone seems to have at the centre of their brains what is best for Warwickshire."

He added: "Although I want to go in, I don't want it to be at any price or at any speed, that would send the wrong message back to our electorate, that we are rushing it. This has to be good for the people of Warwickshire." 

Cllr Seccombe had already committed to a thorough process during her address. 

"To ensure we get a good response and to evaluate that response properly, to build the business case over whether or not this is right for us at this point, we need time," she said. 

"That is why the challenge is the timeframe. What I am not prepared to do is curtail any of that for the sake of speed – we need to do the job, do it properly and manage the outcome fairly."