Why don't the dogs bark? This is one of many questions the thorough forensic scientist should ask when searching for clues to a crime.

You need to be imaginative, meticulous, tenacious, alert, enquiring and good at teamwork. Angela Gallop is obviously all these things – and more – and her new book When the Dogs Don't Bark, describes her fascinating life lived with forensic interest.

Her biology teacher Mrs Thompson lit something inside her and made her actively want to learn, which lead to her studying botany at Sheffield University and eventually becoming the only woman Reporting Officer in the Home Office's Forensic Science Service in Harrogate more than 40 years ago.

Since then she has set up several companies, established new and different ways of looking for and reading clues, and has worked on many much-publicised cases, some of them years after the event following the appearance of new evidence: Stephen Lawrence, James Bulger, Dr David Kelly, Rachel Nickel, Damilola Taylor and even Princess Diana – all these cases benefited from Professor Gallop's exhaustive detective work, and previous miscarriages of justice were set straight.

Just as important as the clues which are visible are those which are not. If the victim has a dog, why did it not bark?

Professor Gallop will be talking tomorrow (Tuesday October 22). Tickets are available via the red button below, by telephone on 01749 834483 or in person at Cedars House, The Liberty, Wells BA5 2ST, or at Cedars Hall on Tuesday afternoon or evening.