Scottish Lib Dem leader steps down

Mr Stephen was elected leader of the Scottish Lib Dems in June 2005. Deputy leader, Michael Moore MP, will now take on responsibility as acting leader.

In a statement, he said: "Everyone involved in politics knows that there are stresses and strains on family life. But when it goes beyond that, when it crosses a line, something has to be done.

"And at that stage - when you have to make a choice between family and politics - there can only be one answer. The health and wellbeing of your family has got to come first. With four children between the ages of 4 and 12, my family has got to be my priority.

"As an MSP representing a constituency well away from Edinburgh, I have been away from home at least four working days each week for more than nine years.

"As a party leader the responsibilities have been even more demanding. You have to be available every day, every week. There is rarely a weekend, a birthday or a family holiday when the demands of the job do not intrude.

"That is not to complain - long hours and long absences from home go with the job. But it can all have an impact. And when that impact becomes too great, it is time to put my family first."

Liberal Democrat leader Nick Clegg said: "Nicol Stephen has been an outstanding politician and force for change in Scotland.

"Liberal Democrats owe him a huge debt of gratitude, and I personally want to thank him for his friendship and dedication to the party. His integrity shines through in taking what must be a very difficult step, but everyone will understand and respect his decision in view of the enormous strains and pressures of combining family life with a hugely demanding role."

Mr Stephen's shock announcement comes less than a week after Scottish Labour leader Wendy Alexander resigned amid a row over leadership donations.