9 August 2011 Last updated at 09:37 ET

Melbourne Scot in plea over missing father Richard Lyon

Richard Lyon has been missing for one week

A Scot living in Australia has flown in from Melbourne to make an appeal for help to find his missing father.

David Lyon, 30, and his mother Noreen, joined officers at Ayr Police Station on Tuesday, as the investigation into Richard Lyon's disappearance continues.

The 59-year-old, from Kirkmichael, South Ayrshire, was last seen by his family at 07:00 on 2 August.

He left his home and was believed to be driving to work in Maybole in his silver Honda CRV.

The last sighting of his car - which has the registration number RJ55 EBP - was about 13:20 on 2 August as it was travelling northbound on the A80 near Castlecary.

'Rather low'

Mr Lyon has not been missing before and his absence from home is said to be completely out of character.

Police said he had been feeling "rather low" lately and his family were now extremely concerned for his wellbeing.

Mr Lyon is described as 5ft 10in tall, of medium build with grey receding hair, and a full beard. He also wears glasses.

He was last seen by his family wearing jeans, a T-shirt and training shoes.

Mr Lyon is a said to be a very keen hillwalker and has climbed many of the Munros.

Ch Insp Neil Kerr, of Strathclyde Police, said: "As time passes we are becoming increasingly concerned for the wellbeing of Mr Lyon.

"I am keen to speak to anyone who may have seen his vehicle as it may lead us to Mr Lyon's location.

"I can confirm that Mr Lyon posted his car and house keys to the family home on Thursday 4th August, so, I would appeal to anyone who may have seen or who knows where the car is currently located."