Holy Trinity church in Prince Consort Road, South Kensington, London, has a striking war memorial to its 43 parishioners who fought and fell during the Great War. They were predominantly residents of the local area and were mainly drawn from the wealthier professional middle classes or minor aristocracy who lived in the South Kensington area at the time.
Prominent among the men listed on the memorial were the three Lucas-Tooth brothers, sons of Sir Robert Lucas Lucas Tooth and Lady Helen Lucas Lucas-Tooth. Sir Robert was a brewer and representative in the Australian Legislative Assembly.’[1] 
The first son to be killed was Captain Douglas Keith Lucas Lucas-Tooth.
He fell on 13 September 1914. He was born on 10 October 1880 and joined the 9th (Queen’s Royal) Lancers in August 1900, seeing action in the Boer War.
The second son to fall was Captain Selwyn Lucas Lucas-Tooth, killed nearly six weeks later on 20 October 1914, while serving with the Lancashire Fusiliers. He was born on 19 March 1879 in Sydney, Australia, and was the eldest of the three sons. Selwyn was sent to school at W. Ratcliff’s Preparatory School, Font Hill, Sussex before going to Eton and then Christ Church College Oxford in 1898.
In 1904, he joined the 5th [Militia] Battalion of the Lancashire Fusiliers being promoted Lieutenant in May 1905. In 1907, he was made a Captain in the 3rd Reserve Battalion.
On his death his Colonel wrote, ‘Captain Lucas-Tooth was commanding one of the companies in the front line, and after, gallantly, leading his company in a successful attack was, on the following day, killed instantaneously in the front trenches. He had only been a short time with the battalion, but from the first he proved himself a capable officer in every way and had won the respect and affection of both officers and men of the regiment. His loss is deplored by all of us.’ Corporal W. Piper wrote, ‘Captain S. Lucas-Tooth was my company officer during the time he was in France and I was with him in the trenches at the time of his death – the news of his death was received by the men of his company as a great shock — he died like a soldier and a gentleman.’[2]
It was said that the death of these two sons may have led to their father Robert suffering a heart attack in February 1915.
Major Sir Archibald Leonard Lucas Lucas-Tooth was the youngest and last brother to be killed. He died on 12 July 1918, aged 34, while serving with the Honourable Artillery Company.[3] He was the last surviving heir to the baronetcy of that was created in 1906. As Archibald had no male heir, his title expired with him.
The three sons of Sir Robert Lucas-Tooth are commemorated in the Kameruka Hall, New South Wales.
Holy Trinity Church have produced a Holy Trinity Remembers WW1 guide giving biographical details on the men listed on their memorial.
[1] The Sydney Morning Herald, 16 July 1918, p.8.
[2] http://www.chch.ox.ac.uk/fallen-alumni/captain-selwyn-lucas-lucas-tooth
[3] https://en.wikipedia.org/wiki/Sir_Archibald_Lucas-Tooth,_2nd_Baronet