On 03 Jul 1914 Denis George William Anson 4th Baronet (age 25) died. His first cousin John Henry Algernon Anson 5th Baronet (age 17) succeeded 5th Baronet Anson of Birch Hall in Lancashire.

News Report Adelaide 'Advertiser' of 10 August 1914:

The tragic deaths of the young baronet, Sir Denis Anson (age 25) and Mr. William Mitchell, who were drowned in the Thames in the early hours of last Friday morning [3 July], were, it seems, brought about by sheer folly born of natural high spirits, stimulated by champagne. Sir Denis, who was only 26 [25] years of age, was the son of the late Mr. Frederick Arthur Anson, of Piraki, New Zealand, and spent the early part of his boyhood in New Zealand. He came to England to be educated at Eton, and later went to Oxford University. He studied law, and a short time ago was called to the bar, and began practice in chambers in Mitre Court, Temple, in the same building where his uncle, the late Sir William Anson (deceased), to whose baronetcy Sir Denis only succeeded about a month ago, had chambers. Sir Denis was the only son of his parents, and the youngest of a family of five. At the time of the tragedy he was living in Half Union-street with his mother and sister.The tragedy had its origin in one of the now fashionable "midnight picnics" up the river. Sir Denis Anson was one of a party of 12 or 14 ladies and gentlemen who boarded a steam launch at Westminster Pier shortly after midnight on Thursday. The party included Count Constantine Beckendorff, a son of the Russian Ambassador, Miss Iris Tree, daughter of the famous actor [Sir Herbert Beerbohm Tree], the Hon. Kasper Ridley (brother of Viscount Ridley), Mr. Raymond Asquith (son of the Prime Minister) and Lady Diana Manners, daughter of the Duke of Rutland, and there were also a number of musicians on board to discourse sweet music during the trip. The party, it appears, took supper whilst the launch was making its way up the river to Hampton Court, and nothing untoward happened until the homeward journey was nearing completion. It seems to have been a very merry party, and Sir Denis appears to have endeavoured to add to the merriment by what schoolboys term "playing the goat" - climbing about the superstructure of the launch and the like. Presently, when the launch was nearing Battersea Bridge Sir Denis announced his intention of diving overboard, and climbed on to the bridge to do so. Captain White, who was in charge of the launch, appears to have prevented him carrying out his intention, and to have cautioned Sir Denis as to his conduct. What actually happened thereafter has produced half a dozen stories, differing materially in detail, but the main facts are clear. Sir Denis was chaffed by some of his companionsabout his threat to dive overboard, and to prove his courage took a header into the river. The ebb tide was running very fast at the time, and the River Thames at this point is full of swirls and eddies, against which a strong swimmer in nature's garb would find it almost useless to struggle. For a man hampered by clothing - even light evening dress, minus coat - it was courting disaster to do what Sir Denis did, even if his swimming abilities were above the ordinary. The unfortunate young fellow seems to have realised the fact that he had over-estimated his powers very quickly, for he called out something which those on the launch who heard his cries took to be an indication that the baronet was in difficulties. Bandsman Mitchell was the first to act. Without waiting to remove his clothing he plunged overboard to the rescue. It was gallant madness, for, clothed was he was, Mitchell could make no sort of fight against the fast running tide, and was carried away. A few seconds after Mitchell's plunge there was another splash, and Count Beckendorff had followed Mitchell's lead. But neither Mitchell nor the Count had gone far before a strangled cry arose from Sir Denis, and a moment later the waters had closed over his head. That was the last seen of the young baronet. Meanwhile the launch had been stopped and put about, and a waterman, who had heard Sir Denis' cry of distress, came upon the scene in a rowing boat. By that tine, however, poor Mitchell had also disappeared, and Count Beckendorff was indire distress, when the waterman came to his rescue and pulled him into the boat. The Count was in an exhausted condition, and but for the timely arrival of the waterman there would have been a triple tragedy. As it was, two men lost their lives. The launch and the rowing-boat cruised about the place where Sir Denis and Mitchell had disappeared for a long time, but of the two poor fellows not a trace could be found. Mitchell's body was washed up by the tide near Battersea Bridge on Saturday morning, but several days elapsed before the mortal remains of Sir Denis Anson were discovered lying beneath a raft of timbers near Lambeth Bridge, some three miles away from the scene of the tragedy. At the inquest a large amount of attention was paid to the question of Sir Denis' sobriety. It was admitted that the young baronet had partaken of wine, but it was strenuously denied by every witness that he was inebriated in any sense of the word. "He was merry and full of life," said the captain of the launch, but was certainly not intoxicated, in the opinion of the skipper. And that was the burden of all the witnesses' testimony. Sir Denis was, as always, full of life and fun, and was the life and soul of the party, but he had not had too much drink. So the jury found a verdict of accidental death, and added thereto the rider tha they found that Sir Denis was "quite sober, but full of fun."