Plans for a new city-based Twenty20 tournament will hinge on the outcome of a postal ballot after England and Wales Cricket Board chairman Colin Graves triggered the referendum process.

Graves took the much-anticipated step at a Lord's meeting of the executive board on Tuesday, after it emerged the previous day that all 18 first-class counties and the MCC had signed up to a "media rights deed" which authorises the ECB to include on their behalf the proposal for the eight-team Twenty20 competition in the governing body's portfolio to offer to prospective broadcasters this summer.

The remaining stumbling block, one which is expected to be overcome by securing a minimum 31 postal votes in favour out of 41 over a forthcoming 28-day period, is the requirement for an amendment to the existing ECB constitution to allow - as a one-off measure - a tournament which includes only eight teams rather than all 18 professional clubs.

The executive board agreed to dispatch the literature - this time to the Minor Counties Cricket Association and 21 recreational boards as well as the counties and MCC - inviting all stakeholders to agree or otherwise with the change in policy which will pave the way for the ECB to run its own high-profile new tournament in July and August from 2020.

Graves, who also announced resolutions to review the ECB's full Articles of Association and governance in line with previously-stated objectives for his tenure, described the board's unanimous decision to formalise the ballot as a "watershed moment".

He said: "The ECB board today gave their unanimous support to trigger a formal process to change the game's Articles of Association and allow a new T20 competition.

"Our members have seen the evidence for why the new T20 proposal is the right way to reach new audiences, create new fans and fuel the future of the game.

Nick Gubbins is bowled by Richard Gleeson during the NatWest T20 Blast quarter-final match between Northamptonshire Steelbacks and Middlesex last August (Getty)

"Together, we can now take a huge opportunity to not only create a deeper engagement with those who currently follow cricket but to attract a whole new audience and ensure the sustainability of our game.

"This is a watershed moment for us all to make the whole game stronger."

There are indications already, over and above universal signatures on the media rights document, that - after a process of persuasion which has included a £1.3million-a-year share of revenue for each county for the first four editions of the new competition - there is likely to be broad approval.

That was also the case six months ago when three counties nonetheless dissented in a 16-3 show-of-hands in favour which gave ECB its initial mandate to press ahead with the eight-team format to the exclusion of other options.

ECB chief executive Tom Harrison confirmed, between presentations of the latest plans at the Royal Institute of British Architects in Marylebone on Monday, that he was no longer aware of any significant doubts among counties about the tournament set to give this country its own version of the Indian Premier League and Big Bash which have been so successful elsewhere.

ECB chairman Colin Graves with Andrew Strauss, director of England cricket (Getty)

Kent and Sussex were among the three counties still to be convinced last September.

Both will coincidentally have important business of their own to attend to at annual general meetings on Tuesday evening, when Kent's George Kennedy and Sussex's Jim May each step aside at the end of a long tenure as chairman.

They make the point that no binding decision has yet been made by their counties, but there seems to be encouragement for the ECB that a full endorsement may be forthcoming.

Kennedy said: "We haven't voted yet, and I will be putting it to the members tonight."

Harrison's assessment that major concerns have been soothed may not be too wide of the mark, though.

Northamptonshire celebrate after winning the Natwest T20 Blast (Getty)

"I think the most important thing we wanted to make sure of was that the financial arrangements were appropriate," added Kennedy.

"The £1.3million for four years is enhanced by a percentage of the revenue post year four ... so financially it looks okay."

Some qualms persist, the most obvious perhaps addressed by the ECB's reassurance that it will be a one-off measure to sanction a tournament which does not involve every club - or indeed any of them, since the teams for 2020 are expected to be separate entities merely using established major stadiums.

"I still think it is a pity all 18 clubs are not involved," said Kennedy.

"The worry is will it spread to the county championship or the one-day competition. But we were very strong on that (clause)."

It is known already that the intention is a structure of 36 matches in 38 days in July and August, running concurrent to Test matches and including a draft of 13 players per squad in salary bands and then two more added on the basis of performances in the NatWest Blast.

Twenty20 cricket could be set to see a new tournament (Getty)

Other specifics will come to light only when broadcast discussions, expected to involve free-to-air television, are advanced.

"I think the fact it is three years away means there will inevitably be some doubts about the details," said Kennedy.

"Will the overseas players flock to it, for example? I also said yesterday I was slightly concerned we would be playing the one-day competition at the same time - and can we be sure sponsors will still support that?

"But I don't intend to stand in the way of progress, and we will probably go along with it."

May, meanwhile, believes assurances and extra information which has been forthcoming have allayed the understandable worries of some.

"The non-host counties had a degree of anxiety about being marginalised," he said.

"But I think they have taken on board a lot of the points made - which is obviously encouraging."

He is loath to speak for the nation, or to commit Sussex to a course which has yet to be ratified.

But at the suggestion many appear to be leaning towards supporting the ECB's plans, he said: "My sense is that most people are in that general direction of travel."