See APPA's Park 27A photo album:
John Ednie Brown (1848-1899) was a sylviculturist (forest expert) who was brought to Adelaide in 1880 to advise on management of the Park Lands. John E Brown literally wrote the book on trees in the Adelaide Park Lands and beyond. His 1880 book "A Practical Treatise on Tree Culture in South Australia" was used as a guide by City Council gardeners for decades afterwards.
It was only in September 2017 that the City Council decided to name this Park after him.
Adelaide City Council does not (yet) have a Park 27A web page