According to the Circular No. 43/56 dated 28 th August,1956 of BOARD OF SECONDARY EDUCATION,WEST BENGAL:-
Ref. : Confirmation of the service of a teacher.( see third para)
In case of unaided High Schools, the probationary period of a teacher shall be six months as laid down in the Revised School Code. A confirmed teacher of unaided school when appointed in an aided school should serve a probationary period of two years in the aided school before he can be confirmed.
Thank you.