HOLYROOD officials asked the prison service whether a jailed MSP could carry out his job before recommending that Bill Walker be stripped of 90% of his salary if he is given a custodial sentence.

Parliament's ruling body ­recommended that the MSP suffer this sanction for any term served after his conviction for 23 assaults against women, while stressing it should apply to any MSP who does time, even on remand.

The cross-party Scottish ­Parliament Corporate Body (SPCB), which oversees the running of Holyrood, decided on legal advice that this was the biggest sanction it could invoke.

The Parliament's lawyers even contacted the Scottish Prison Service to find out how much of an MSP's role could be conducted from jail.

Issues that could arise include the confidentiality of constituents' mail, as prisoner correspondence is monitored, and possible lack of access to telephones and ­computers, even in an open prison.

In her letter to MSPs following the corporate body she convened, Presiding Officer Trisha Marwick said: "The SPCB is strongly persuaded by the proposition that any member unable to carry out their full range of functions as a result of being imprisoned should not receive their full salary.

"From reviewing the core functions of a member as set out in the SPCB paper, we recommend that 90% of salary should be withheld for the duration of imprisonment.

"I shall therefore be seeking the Parliamentary Bureau's agreement to bring forward a resolution before Parliament next week to amend the Salary Scheme."

She said legal advice had stressed the principle of salary in return for performance, that the move should "not be motivated by punishment, retribution or censure", and action should be proportionate and applicable to all MSPs.

She added: "Having looked ­carefully at the powers available to this ­Parliament, the SPCB is clear this is the right thing to do and hope members will support this course of action."

A five-page briefing from ­officials informed the recommendation. It said that disqualification of a parliamentarian or a right of recall for electors were only within the legislative competence of Westminster, while Holyrood's code of conduct "specifically excludes a member's private and family life."

However, Holyrood does control salaries and would have a power to relate this to the ability to function as an MSP.

The docking of 90% of Walker's pay for any period in prison will not satisfy those who have called for him to step down. His expulsion from the SNP costs him his committee positions, while there are now moves to expel him from specialist cross-party groups. He faces a maximum sentence of 12 months when he is sentenced.

Liberal Democrat leader Willie Rennie, whose motion urging Walker to quit has been backed by more than 90 MSPs, said: "These are constructive and proportionate proposals.

"It would be entirely wrong for any person holding public office while in prison to receive pay for a role they are not fulfilling. I hope members will support these measures when they come before parliament next week.

"We must be clear that there can be no let-up in our efforts to seek ways to remove Bill Walker from parliament."