Hi, I am actually not from London but lived there for a few years.
The interesting fact is that over 40% of the population in Perth are not from Perth and many of the tour guides are not necessarily native of Perth. I have been conducting tours in Perth for the last 16 years and have experience as a tour guide for over 24 years. A tour guide should not be judge by his or her origin but by the work he or she offers. I offer private tours in 4 different languages including English , with passion and dedication. Not many "native" tour guides actually speak a foreign language either than English. I have had many excellent reviews from people who appreciate what I have to offer.
Kind regards, Sergio Libertino