The main building of Wellesley College has been a local landmark for nearly a century, first as a rest stop for ferry passengers, and, since 1913, as a school where a number of children from the Eastbourne and wider Wellington community have received their education.

From at least the 1850s the eastern bays of Wellington Harbour were favoured by Wellingtonians as a holiday destination. People would take the ferry across the harbour for a day's fishing, picnicking or swimming. During the 1880s the popularity of the bays increased as land around Wellington and the Hutt Valley was further developed or subdivided for farming.

In 1886 Captain W. B. Williams and his son J. H. (James) Williams began offering regular ferry excursions to Lowry Bay and Somes/Matiu Island. After his father died in1890, J.H. Williams took over the business and, in 1894, acquired land at Days Bay. Here he built recreational facilities for visitors to the bay, including a wharf in 1895 (registered Category II by the NZHPT), and a pavilion in 1897 (destroyed by fire in 1952). At this time it was not unusual during public holidays and fine weekends for up to 5,000 people to visit the bay. In 1900 Williams registered his business as a public company, under the name the "Wellington Steam Ferry Company". With the money raised from the share issue, Williams built a large hotel/accommodation house.

Days Bay House was designed by the Wellington-based architect, William Charles Chatfield. It was built at a cost of £9,000, and provided accommodation for up to 50 guests and their servants. A large sitting room, with bay windows, provided excellent views of the bay and harbour beyond. Completed in 1903, it marked a further period of expansion at Days Bay for Williams, including the construction of tennis courts, hockey courts, cricket grounds, and the planting of exotic trees.

In 1905 Williams sold his shares in Wellington Steam Ferry Company to the Miramar Ferry Company. The new owners continued to develop the Days Bay resort. However the hotel venture was not a great success. There were difficulties finding and retaining staff in what was then a relatively remote location. Many of the visitors to the bay tended to prefer day trips rather than overnight or longer stays. By the end of the first decade of the twentieth century the popularity of the eastern bays as a holiday destination had declined. In 1913 Days Bay House was sold to E. G. (Gladys) Sommerville who relocated her private school, known as Croydon Preparatory School for Boys, to the building. The remaining estate was sold to the Wellington City Council and the land was developed into Williams Park.

Croydon opened in February 1914 as a boarding school for a small number of pupils. For a brief period of time Arthur Porritt (1900-1994), later Olympic athlete, doctor and the first New Zealand-born Governor General, taught at the school. In 1919 Croydon was bought by the Anglican Church, which used the building as a boarding school. However, the school retained the name Croydon. In 1940 the Anglican Diocese leased the property to W. H. Stevens, who transferred his day school, Wellesley College, from Wellington to Croydon, and the two schools were merged. The connection with the Anglican Church was maintained by a clause in the lease requiring the school to provide a Christian education. The school stopped taking borders in 1970. Today Wellesley Independent Primary School for Boys provides a primary education for about 250 boys.

Wellesley College has great local and regional significance as it is, along with the Days Bay Wharf, the most tangible reminder of Eastbourne's heyday as a holiday resort. For most of its existence it has been the main building in a school where thousands of children from Eastbourne and the wider Wellington community have received an education.