I thought this was obvious but reading some recent issues and news threads I guess it's not.
2007 Constitution, imposed by the Military.
Section 20. While there is no Regent under section 18 or section 19, the President of the Privy Council shall be Regent pro tempore.
President of the Privy Council of Thailand: General(ret.) Prem Tinsulanonda
For those with eyes to see and ears to hear that should help make some sense of certain happenings. For those who can read Thai and who keep up with "subversive" publications this is the reason for certain epithets being applied to the name of the estimable General and ex PM.