Councillor John Bint said the signs were on the boundary of Milton Keynes which is a "borough and a county" and it was "not an inappropriate use of money".
There have been no boundary changes to this constituency in recent times, but local politics have been drastically altered by the abolition of the county of Humberside.
Twenty20 cricket, which involves batsmen sitting on the boundary edge waiting to go in and bowlers given reduced time to get through their overs, was first launched in county cricket in 2002.