The origin of the Placename Betlow

I was recently asked about the origin of the surname Betlow and whether it was associated with Betlow Farm, near Tring, in Hertfordshire. I replied:

Surnames only started in medieval times and spellings only started to be standardised after the invention of printing and in some cases current spellings (both surnames and place names) may be only a hundred years old.  As a result any analysis of the origins of a surname must involve a large degree of uncertainty.
Some surnames came into existance because someone was named after the place where they came from. It is therefore possible possible that your surname "Betlow" refers back to someone who lived at a place called "Betlow."
The earliest known reference to the Hertfordshire village/manor of "Betelawe"was in 1203 with other 13th century references being to "Betelowe," " Betelaue" and "Bettelawe." The village was abandoned in the Middle Ages (possibly due to the Black Death) and for many centuries all that remained of the manor was a single farm.

The Moat at Moat Farm, Marsworth, undoubtedly dug to drain the central area for the Farm

 "The Placenames of Hertfordshire" suggests that the placename probably was a descriptive term meaning Beta's mound or hill.  The area around Betlow Farm is vey flat - so it clearly doesn't refer to a hill. I haven't visited the Farm but I know much of the area would have been very wet in the past - perhaps even marshy - although moden drainage has lowered the water table. So it is possible that there was a slightly raised area which was drained well enough to build a house.  Not many miles away there are moated sites (often with no surviving buildings, where the effect of the moat was almost certainly to leave a dry area on which a wooden farm house could be built. In the nearby Village of Long Marston the old church is on a mound perhaps 3 feet higher that the surrounding fields - with the remains of a waterfiled moat close by - possible for that reason.