Glencairn is of state historical and architectural Significance. It is important as one of the oldest surviving buildings in the Coburg district and for its long association with the Mailer family. Its architectural Significance derives from its early date, high degree of integrity and sequence of sympathetic alterations, which have resulted in a highly unusual, somewhat picturesque composition.
The mature front garden, now restored, is also of Significance. The manner of its present form probably dates from the first period of alterations. The form is typical for a larger suburban house of the 1880s and is one of the few surviving in metropolitan Melbourne.