Kerr was born in 1940, in Lossiemouth, Moray, but since his early childhood has lived (on and off) in East Lothian. Having left school, Kerr joined the Civil Service as an Executive. In the early 1960s he moved to London to pursue a career as a professional jazz musician, touring with the Clyde Valley Stompers and recording for producer George Martin (who also produced for The Beatles). Kerr, on the clarinet, was the leader of the band.

The Clyde Valley Stompers produced many successful hits, one of which was the great "Peter and the Wolf". The band appeared on several television programs including The Morecambe and Wise show and Thank Your Lucky Stars. In 1970, he took to farming barley and beef cattle back in East Lothian, and was also heavily involved in record production. His "Amazing Grace", produced for the Royal Scots Dragoon Guards, sold approximately 13 million records and became the best selling instrumental record ever.

These days, Kerr concentrates his creative energies on writing books. The award-winning Snowball Oranges and Manana, Manana, followed by Viva Mallorca!, A Basketful of Snowflakes and From Paella to Porridge (Summersdale Publishers) form a series of often hilarious accounts of his adventures and misadventures while trying to grow oranges for a living on the Spanish island of Majorca. His Thistle Soup is an amusing yet poignant memoir of Kerr's childhood in the Scottish countryside and of his attempts to follow in his farming grandfather's footsteps.

In August 2006 Kerr launched a new fiction series with the publication of Bob Burns Investigates - The Mallorca Connection (Accent Press), a humour-laced mystery set in Scotland and Spain. This was followed by two more tongue-in-cheek Bob Burns mysteries, The Sporran Connection and The Cruise Connection, also a town-meets-country caper entitled Fiddler On the Make and a humorous romantic adventure called The Gannet Has Landed.

Much of his work has associations with Mallorca, and in 2009 he began writing Song of the Eight Winds, a historical novel also set on the Spanish Mediterranean island.