He was born in Bombay, India and was educated at Bath Grammar School and Peterhouse, Cambridge, receiving a BA in 1822 and an MA in 1825.

At Ash Island the sisters helped their father in his entomological work, collecting, preparing and drying specimens of plants and insects, and also accepted painting, drawing and lithography commissions from Australian naturalists including Gerard Krefft, William Macleay, Thomas Sutcliffe Mort, Edward Pierson Ramsay, William Woolls and Ferdinand von Mueller.

Although published (in London : John van Voorst) under Alexander Walker Scott it was an entirely collaborative work as its title states.

[4] Alexander Walker Scott was a trustee of the Australian Museum 1862–79 and a Fellow of The Entomological Society of New South Wales, founded in 1862, as were both Helena and Harriet, though in their case it was honorary, a rare distinction.

In 1842 Scott invited French explorer and artist Fredrich Wilhelm Ludwig Leichardt to stay at his house and arrived on 23 September and spent 3–4 days there.