Arthur Macnamara (1831 – 11 February 1906), was a squire of Billington near Leighton Buzzard in Bedfordshire, England. He is known for building in and improving the village of Billington.
Macnamara was born on Grosvenor Street in London in 1831. His family was wealthy; the Macnamara family owned many buildings, including a castle at Llangoed, Wales, a country house called Caddington Hall in Hertfordshire, and an estate at Eaton Bray in Bedfordshire.
On 28 September 1854, Macnamara married Lady Sophia Hare, daughter of the local MP for St Alban's the 2nd, Earl of Listowel. The couple were married in the bride's family estate at Ballyhooly in County Cork, Ireland. The couple then established their home at Caddington Hall.
At that time, young Macnamara developed a passion for building. He embarked on the project of re-creating the lost castle of Eaton Bray on some land bequeathed to him by his mother. After building grandiose lodges and clearing and preparing the moated site, he seemed to abandon the idea, probably due to lack of funds. All was not well in his marriage, either. Sophia's father, a Lord-in-Waiting to Queen Victoria, was able to secure his daughter a position as a Lady-in-Waiting to the Queen's daughter, Princess Louise, Duchess of Argyll.
In the early 1880s, Macnamara began to acquire land and cottages at Billington and embarked on an ambitious building project, perhaps inspired by the building of Mentmore by Baron Mayer de Rothschild, which was only five miles away.