Evelyn Boscawen, son of Reverend the Honourable John Evelyn Boscawen, vicar of Ticehurst and a canon at Canterbury, attended Eton and Oxford and was called to the Bar in 1841. In 1845 he married Mary Frances Elizabeth Stapleton, 17th Baroness le Despencer, who brought with her Mereworth Castle, near Maidstone, Kent.

Mereworth (pronounced Merryworth) Castle is a Palladian villa, erected in 1723 by Colen Campbell for John Fane, later 7th Earl of Westmorland and 14th Baron le Despencer on the site of the original fortified manor house, of which nothing visible remains. At his own expense, Fane relocated the village of Mereworth to improve the view from Mereworth Castle, which served in 1967 as a location for the movie "Casino Royale".

Upon the death of John Fane without a male heir in 1762, the barony of le Despencer fell into abeyance. It has been revived twice for the descendants of his sisters, most recently for Thomas Stapleton, who became the 16th Baron le Despencer in 1788. It was Thomas Stapleton's granddaughter who succeeded as the 17th Baroness le Despencer in 1831. For her husband, Evelyn Boscawen, Mereworth Castle became the site of an extensive and successful stud.

In 1852 he succeeded to the family seat of the Boscawens at Tregothnan, near Truro in Cornwall, and to the title of Viscount on the early death of his cousin George, the earldom having become defunct with the latter's passing.

He entered the sport under the name of "Mr Valentine" and put his horses in training, first with John Scott at Malton and following Scott's death with Mathew Dawson at Newmarket.Although the first classics winner to appear in his "magpie" colours was the One Thousand Guineas winner Hurricane (b f 1859 Wild Dayrell) his first homebred winner was Queen Bertha (b f 1860 Kingston), bred from from Flax, and winner of the next year's Oaks Stakes. Flax also produced Reginella (b f 1862 King Tom), dam of the Lincolnshire Handicap winner Guy Dayrell (b c 1867 Wild Dayrell), and the stallion Honiton (b c 1863 Stockwell).

Lord Falmouth's broodmares, left to right: Hurricane with filly Cataclysm Handicraft with dam Woodcraft Queen Bertha with filly Spinaway

From this point Mereworth produced its own classics winners. Hurricane foaled the Two Thousand Guineas winner Atlantic (ch c 1871 Thormanby) and Queen Bertha foaled Spinaway (b f 1872 Macaroni) and  Wheel of Fortune (b f 1876 Adventurer), both One Thousand Guineas and Oaks winners.

Mr Graham won the Oaks with the Mereworth-bred Gamos (ch f 1867 Saunterer). Spinaway foaled Busybody (b f 1881 Petrarch) who sold for 8800 guineas to Mr G A Baird at Lord Falmouth's sale at Newmarket in 1884 and promptly rewarded her new owner with wins in the Guineas and Oaks. Harvester (br c 1881 Sterling), also sold in the dispersal sale, went on to run a dead heat with St Gatien (b c 1881 The Rover) for the Derby in the colours of Sir J Willoughby.

Mereworth won the Two Thousand Guineas with Charibert (ch c 1876 Thormanby) and Galliard (br c 1880 Galopin), the Derby with Kingcraft (b c 1867 King Tom) and Silvio (b c 1874 Blair Athol), the One Thousand Guineas with Cecilia (b f 1870 Blair Athol) and Jannette (b f 1875 Lord Clifden) and the St Leger with Silvio, Jannette, and Dutch Oven (br f 1879 Dutch Skater).

Altogther Lord Falmouth bred the winners of nineteen classic races, owned the winners of sixteen and accumulated over £300,000 in winnings.

His son, Evelyn Edward Thomas Boscawen (1847-1918), 7th Viscount Falmouth and 18th Baron le Despencer, bred the One Thousand Guineas winner Quintessence (b f 1900 St. Frusquin) and the Two Thousand Guineas winner Clarissimus (ch c 1913 Radium).