When I visited Cudlow House a few years ago the owners kindly explained how the Llewellyn Davies family came to spend summer holidays there: Arthur and Sylvia first visited Rustington in 1891 as guests of their friend Sir Hubert Parry, the composer, who had lived at Cudlow House between 1878 and 1881, and then had moved into a new house (Knightscroft House) on the other side of Sea Road. Evidently, Parry provided the new owners of Cudlow House (the Hoper ladies: Dorothea, Edith, Emma Grace, and Mary Winifred) with some of their visitors, although this wasn't made clear to me. Other visitors to Cudlow House in those days included Thomas Hardy.
In the summer of 1906 it was Sylvia's mother, Emma du Maurier, who rented Cudlow House, and the Llewellyn Davies family, plus Barrie, were therefore Emma's guests. The Davies boys spent much of the time playing cricket and tennis on the lawn, and playing on the pebbly beach and in the sea just a few hundred yards away. My grandmother, Mabel Llewellyn, was also there for about three weeks during that long holiday, As Barrie's housekeeper, Mabel was summoned by Barrie to leave Black Lake Cottage and come and work at Cudlow House, reportedly* to teach the younger of the Davies boys to swim because their nursery governess, who had gone with them, couldn't swim. While Barrie doubtless organised and joined in the games of cricket, it seems that the seaside was not to his liking: the one holiday more miserable than all the others when you "wander along the weary beach, fling pebbles at the sea and wonder how long it will be until dinner time".
*Source: "More about Barrie and Hanny", John o' London Weekly, November 13th, 1953.