SIR Muir Russell, Glasgow University's principal, has issued a rallying cry to students to cast their nominations for the rector's vacancy.

For the first time in the university's history, students failed to nominate a candidate for the post in February of this year to take over from Greg Hemphill, the comedian, who completed his term in March.

It was the latest blow to the rector's role, which has gradually diminished in power over the years and is now regarded as an honorary position.

With the university court preparing to set a new date for a rescheduled election in the autumn, Sir Muir has stressed to students the importance of having a rector.

He said: ''There is no lack of political involvement on the part of the student body in Glasgow - why this particular manifestation didn't happen I really don't know.

''I should like there to be a rector representing the students. If there is not one, it means there is one less route by which the students' position can be safeguarded and represented,'' he said.

''It is a great tradition having someone who does that job.''

Legally, the university court can still operate without a rector being there to carry out the duty of chairman of the court.

Several potential candidates are believed to have been formally approached about the vacant position at the beginning of the year, including Kirsty Wark, the broadcaster, Sir Menzies Campbell, Liberal Democrat deputy leader, and John Simpson, the journalist, but all declared themselves out of the running due to other commitments.

As with other universities of medieval foundation, the rector was originally the active head of the university, exercising jurisdiction over all its members and elected by the votes of their nations.

Since 1858, the rector has been elected every three years by matriculated students.

The office gradually has become a symbolic post and, recently, the tendency has been for students to nominate television celebrities.

Whereas once the post of rector was filled by figures such as Sir Compton Mackenzie, Benjamin Disraeli and Sir John Boyd-Orr, the mantle has in recent years been taken over by Richard Wilson, the actor, and Johnny Ball, the former children's television presenter.

In 2000, Ross Kemp, the former EastEnders actor, resigned halfway through his three-year term as rector at Glasgow because of his work demands.

He was criticised after missing an engagement to speak during Freshers' Week for the second year in a row.

At the time, Marilyn Crosser, then president of the Students' Representative Council, admitted that students were unrealistic in their attempts to secure a high-profile rector who would be able to devote time and energy to the position.

Hemphill said: ''I was impressed by the day-to-day enthusiasm of the students during my time as rector. My door was getting knocked every other day and I tried to help with a range of issues.

''Students care about a variety of things and I was glad to try to help them.

''It's a great post, one which needs someone to stand up and represent the students.

''I'm sure somebody will enjoy stepping into it.''