[1] His mother was the daughter of Reverend William Burnside DD (1751–1806), minister of St Michael's Church, Dumfries and a friend of the poet Robert Burns.
[9] Until that time several surgeons, including James Syme and John Argyll Robertson, had undertaken ophthalmic operations as there was no specialist department of ophthalmology.
[12] When processing calotypes he showed a surgeon's concern with both care in the manipulation of the paper and 'the strictest attention to cleanliness...' He believed that 'the best prints were obtained from an unwaxed negative as the...half tints were much more delicate.
[15] Such was the importance of photography in his life that when his presidential portrait was commissioned by the RCSEd, he elected to be portrayed with a photograph in his hand rather than the more usual surgical book or instrument.
[16][17] When the Ophthalmological Society (later the Royal College of Ophthalmologists) was founded by Sir William Bowman in 1880, Walker was elected vice president.