From a London address, Wood notes that Lomax exhibited three scenes of Venice at the RA (1889-91). He was the son of a Barrister at law who worked from London and Suffolk.  Though a member of STIAC, extensive contact with Cornwall cannot realistically be shown.  Correspondent Tony Copsey has provided a biography (2013), for which many thanks:

Born at Kensington, London in 1853, son of Thomas Lomax, a barrister, and his wife Ann née Chadwick, who married at Kensington in 1853. In 1861 the family lived at 15 Clarendon Road, St Mary Abbots, Kensington but by 1871 they had taken Grove Park, Yoxford, Suffolk when John was an undergraduate at Cambridge. In 1881 the family were still at Yoxford but John was not present but was of Yoxford when a member and exhibitor at the Ipswich Fine Art Club 1885-1916. In 1891 the 37 year old landscape painter, John was living at Grove Park with his parents, 65 year old Thomas and 64 year old Ann, both born at Rochdale and three of his siblings and they retained eight indoor servants. John, exhibited at Manchester City Art Gallery, New Gallery and the Royal Academy 1889-1896 from London in 1889 and Yoxford in 1891.

He married at St. George’s Hanover Square, London in 1897, Hester St. Clair B née Johnson, and is found in 1901 a 47 year old artist living on own means’ at Drinkstone House, Drinkstone Green, Suffolk with his 31 year old wife Hester, born China and their 2 year old son Cecil, born Knightsbridge, London and retained six indoor staff. In 1911 John and his wife were visitors to his brother, Charles Henry Lomax, a barrister, at his former parents' home at Grove Park, Yoxford. 

Lomax died at Kensington, London in 1916, aged 63 and his wife died at Folkestone in 1962, aged 91. His son Cecil married Hon. Elizabeth Margaret Brand, daughter of the 3rd Viscount Hampden and daughter Pamela married Sir Robert Alexander Abercromby, 9th Bt. of Birkenbog