“ :Provided that nothing in this section shall preclude a person from being given legal aid in connection with summary proceedings after conviction and before sentence where the court is considering a sentence of imprisonment or detention or the imposition of imprisonment, or detention, under section 396(2) of the Criminal Procedure (Scotland) Act 1975 in respect of failure to pay a fine, and he has not previously been sentenced to imprisonment, or detention as defined in section 41(2)(b) of the Criminal Justice (Scotland) Act 1980. ”..