This is a "lost" location surname, which derives either from a former medieval village or from some existing site of which the most likely source would be Hensting near Winchester. The "modern" surname is almost certainly a dialectal corruption, as it has no meaning, and all names originally had a meaning. The translation of Hensting is the place of the horses, from the Olde English "hengest" which strictly speaking describes a stallion. It is not easy to see how "Hengest" developed into "Hensting" and then "Instril" in 1645 (see below), but dialectal transposition is common, and occasionally the only connection between the original form and the later surname is one of two letters! An extreme example is Carruthers which is found in the North East as Cruddas, after which anything is possible. What we can say with certainty is that this surname is various forms has been recorded in Hampshire since the 17th century, and these examples include William Enstrell who married Martha Creswick at Hannington on May 6th 1771, Thomas Instril, who was christened at Micheldever on March 2nd 1800, and Thomas Instrell, who married Harriet Noice at Basingstoke, on April 14th 1836. The first recorded spelling of the family name is shown to be that of John Instrell, which was dated November 24th 1645, married Jane Carter at Elvetham, Hants, during the reign of King Charles 1, known as "The Martyr" 1625 - 1649. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.