There are approximately 22,045 people named Dennis in the UK. Approximately 349 out of every million people in the UK are named Dennis.
"It derives from "Dionysios" meaning "the divine one of Nysa", a reference to an early god, who was believed to be the protector of the vine. It is also said that Nysa was a mountain in the modern Afghanistan, where celebrations were held by the Greek army of Alexander, The Great. Whilst St Denis, the bishop of Paris, France, was an early Christian martyr of the 3rd century a.d., it must be said that like most surnames of Christian origins, the "modern" surname owes its popularity to the famous "crusades" of the 12th century, when successive European kings launched expeditions to free the Holy Land from the Saracens. ... The first recording of the family name anywhere in the world and in any spelling is believed to be that of Walter Denys, a witness in the year 1272, at the Assize Court of the county of Staffordshire. This was during the reign of King Henry 111 of England, 1216 - 1272." - the Internet Surname Database
Early Mentions
There are four entries for the Denys surname in the Lay Subsidy roll of 1334/5. The least promising are probably:
While we may descend from any of these people, our branch of the Dennis/Denys family appeared in East Malling, Twyford Hundred, during the late 1500's. This makes the following entry of interest: John Denys in Twyford Hundred assessed 2 shillings.
Real estate transaction from 1419/20 at Igtham, about 9 miles from East Peckham, in the Hundred of Wrotham - (254) Westminster: Michaelmas in 3 weeks 6 Henry V; Octave of Hilary same year Q. Roger Rye of Canterbury, John atte Berton and John Denys of Ikham D. Robert Clyfford of Welle Esquire!/2 of the manor of Newelond held by Henry Colbeche and wife Margery for the life of Margery of the inheritance of Robert with reversion to Robert and his heirs. To remain after the death of Margery to Roger, John and John and the heirs of John Denys. Roger, John and John gave 40 marks Henry and Margery were present and did fealty to Roger, John and John.