Dorothy recalls playing hide and seek in the dungeons of one of those castles, Pembroke Castle - the birthplace of the first Tudor King, Henry VII - and of the damage caused by the cannonballs of Oliver Cromwell's artillery.
''These old buildings and their stories inspired me to become a teacher of history,'' she says.
As a teacher in North London, Dorothy was ideally placed for visits with students to the capital's historic buildings to give life to the events she was teaching.
Deciding to see some of the world in 1959, with the New Zealand Government paying her fare, she arrived in New Zealand.
It was never her intention to settle permanently, but she did.
''And I've been a very happy immigrant ever since. However, I did miss the old buildings of Britain and Europe, so when I discovered the old mission house at The Elms and its beautiful garden... I vowed that when my children had fled the nest, I would train to be a guide there.''
Until very recently she has happily guided visitors around the mission house and its grounds and is a font of knowledge.
''The mission house itself is an elegant example of a Georgian Regency bungalow, and what makes it number two on Heritage New Zealand's list of important historic New Zealand houses is the fact that of all the mission houses built in the North Island in the 1820s to 50s, ours is the one that is still in its most original condition. Others might be older, but thanks go to the Maxwell family, descendants of the second wife of the missionary Alfred Brown, for their determination to keep it open and unchanged to the public so that they could tell its story.''
The family sold the property to a charitable trust, The Elms Foundation, which allows it to be enjoyed by all.
One of the oaks in the gardens was planted as a seedling in 1838.
''[The garden] is now recognised on the list of New Zealand gardens of national significance and it has been another magnet to draw me back there most weekends.
''I will miss the beauty and serenity of the place as well as the company of the permanent staff, the other guides and the many interesting and interested visitors.
''We used to be very busy with visitors coming off cruise ships but now, of course, things are much quieter.''
The Elms manager Andrew Gregg says over the 20-plus years Dorothy has been a guide, she has contributed to the spirit of the mission station and its warm and friendly atmosphere.
''We are very sad to see her go, but we respect her decision and look forward to maintaining a connection with her,'' he says.
It is not unheard of, but rare, for a guide to have volunteered for more than 20 years.
''Dorothy is one of a few who have contributed that level of service," Andrew says.
''Our guides are essentially the lifeblood of our organisation and they are all volunteers. They are people who come from all walks of life and different backgrounds and they give so generously of their time and skills and knowledge. They really bring this place to life for people, through their enthusiasm and their commitment and, in the case of Dorothy, over multiple years.
''What's very gratifying is when we see some of the reviews that are posted online about our tours, some individuals are actually mentioned by name, and Dorothy's one of those. It's an incredible compliment to the way they conduct themselves and the manner in which they bring this wonderful heritage site to life.''
Andrew says the trust is always happy to hear from people wanting to be volunteer guides.
''We provide a really warm and friendly environment where we help to equip our guides with the skills and knowledge they need to perform their function of guiding. Our existing guide team really cherishes their time with us and they meet really interesting people with different backgrounds from all parts of the world and really enjoy connecting them to this place and its stories, which are of national significance. It's an incredibly rewarding role to be engaged in.''
An interest in New Zealand history, an ability to relate to a wide variety of people and a warm friendly manner are all volunteers need.
Dorothy says that, while reluctant, she felt now was the right time to retire.
''I am approaching 86 years of age and in danger of becoming a traffic hazard/statistic while travelling from Te Puke to Tauranga and back,'' she says.
There is a second reason.
''I could not have done all this guiding without the help of my kind husband, retired solicitor Roger Gibbs, but I need to be at home now to rein in his desire to restore law and order to our garden - with a chainsaw.''
