it was the country home of W. S. Gilbert (of Savoy opera fame) – he suffered a heart attack and drowned while trying to save a swimmer in the lake in the grounds. It is now an hotel and is often used as a film setting. The house and gatehouse are listed buildings. History Grim's Dyke may have been built by the Catuvellauni tribe as a defence against the Romans. or as a boundary marker. An excavation in 1979 in the grounds of the Grim's Dyke Hotel gave a radiocarbon date of 50 AD ± 80 years, for a heath in the bank which suggests an Iron Age or Roman date. There is another earthwork close by in Pear Wood, Brockley Hill that has been suggested as an eastern continuation of the Grim's Dyke. This monument is of Roman or post-Roman date and runs at ninety degrees to Watling Street. Trivia The earthwork gave its name to the telephone exchange for Stanmore. The legacy is the first three numbers of many local landlines. References Notes References Archaeological sites in London Archaeological sites in Hertfordshire Parks and open spaces in the London Borough of Harrow Hills of Hertfordshire Ancient dikes History of the London Borough of Harrow Linear earthworks