He married Joanna Susan Hirsch in 1959 and they had two sons, James Brooke and Joshua Alexander, and two daughters, Iona Heloise and Rebecca Alexandra.
In the Sunday Times Rich List 2012, Tanlaw and his family were ranked equal 63rd in Scotland, with an estimated fortune of £85 million.
He attended the chamber and voted regularly, and took a particular interest in debates concerning energy conservation, global warming and the environment.
[4] A keen amateur horologist, Lord Tanlaw is a Fellow of both the Royal Astronomical Society and the British Horological Institute.
In 2005, he introduced the Lighter Evenings (Experiment) Bill, which would move the United Kingdom's time zone forward by one hour, to UTC+1 in the winter and UTC+2 in the summer, for a trial period of three years.
Opponents fear that it would have an adverse effect on people living in Scotland and northern England, where the mornings would be much darker.
Most of his last appearances in the House of Lords was to argue for lighter evenings, which he did when there was only the most tenuous link to the topic being debated in the chamber.