Meaning

The definition of the Eastlake surname only appears in a handful of surname dictionaries but they agree that it derives from Old English ēast lacu, defined as ‘Dweller at the East Lake’, or more generally from the Lake surname, ‘Dweller by the Water’. Henry Harrison’s dictionary points out that in Devonshire a lake is ‘any small rivulet’.

Topographical surnames were common in Devon and by the time of the 1332 Lay Subsidy the surname ‘Lake’ was already prevalent. My first assumption was that Byestelake was a topographical surname named after a natural feature, as I would have assumed for other similar names ending in ‘lake’ which are recorded in medieval Devon. However, the medieval references to the Eastlake surname as a place indicate that it was locative, derived from a place-name, and that those who bore the hereditary surname were resident at the place no later than the 14th century. The evidence fits well with one of David Postles’ conclusions regarding Devon surnames:

One distinctive aspect of naming in the county [of Devon] in the middle ages was the high proportion of locative surnames. Although the level declined over the later middle ages, yet a very large number of surnames – derived from local places in the county – persisted into modern times. Amongst the corpus were surnames derived from place-names which were in turn derived from topographical features.

A key reason that these locative surnames were so prevalent was the dispersed nature of settlement in Devon, especially in areas such as the west of Devon and other rural settings. The names could easily refer to one small hamlet or farmstead like Eastlake Farm.

Eastlake Farm Rivers

But which rivulet did Byestelake originally refer to? The farm today sits within the fork of the River Wolf and River Thrushel. In the late 1900s, the River Wolf was chosen partly for its purity as the source of the massive Roadford Reservoir which now serves as the main fresh water supply for the southwest peninsula of England. Eastlake Farm is to the east of the River Wolf and David Postle’s research on Devon place-names supports the proposition that this is the river which gave rise to the Byestelake name recorded in 1244:

Names like Eastwood, Northway, have commonly been interpreted as ‘east wood’, ‘north way’. The Devon evidence suggests beyond any possibility of ambiguity that in many of these names we have the short form of old compounds bi eastan wuda, bi nor pan wege, ‘to the east of the wood’, ‘to the north of the way’ … ‘Walter Bysudebrok’ lived ‘to the south of the brook’.

So Byestelake is interpreted as ‘to the east of the rivulet’, corresponding with the location of the farm.

Sources:
Henry Harrison, Surnames of the United Kingdom: A Concise Etymological Dictionary, (Genealogical Publishing Company, 1969).
David Postles, The Surnames of Devon, (Leopard’s Head Press, 1995).