Couelegh and Covelav in Anglo-Saxon Records for the various counties dated 949 to 1066) derive their names from the Old English pre 7th Century ‘Cufan Leah’ meaning 'the wood or clearing (leah) of ‘Cufa’ the byname form ‘Cufl’ meaning block or stump.  
Cowley in Gloucestershire, appearing as Kulege in the Domesday Book of 1086, is so called from the Old English ‘Cu-leah’ meaning ‘clearing where cows grazed’.  Two in Derbyshire recorded as ‘Collei’ in the Domesday Book, derive their first element from the Old English ‘col’ meaning ‘charcoal’ - hence ‘clearing where charcoal was burned’.  Finally, Cowley in Middlesex translates as ‘leah in a cofa’  (recess or creek).

The first recorded spelling of the family name is that of Osbert de Couela in 1167 in 'The Pipe Rolls of Oxfordshire', during the reign of King Henry II, The Builder of Churches, 1154 - 1189. “

The following text is from a web page on the origin of the name Cowley - use of English and grammar corrected!  I have not been able to check the validity of the research but reproduce it here for interest.  (The picture to the left, from the same web site, is allegedly the Cowley coat of arms but who or what it relates to I have no idea!  But who am I to renounce our armorial bearings!)

“This name is of English locational origin from any of the several places thus called. Cowley in Buckinghamshire, Oxfordshire, Devonshire and Staffordshire (recorded respectively as Cufanlea, Couela,           

The map to the left shows the number of Cowleys resident in England and Wales in 1891.  (This is actually the only distribution map that I have been able to find thus far.)

I was surprised to see that, given our own associations with Brighton, the highest concentration of Cowleys is actually in the North West, with a small pocket in the London area.

According to current information on the website http://sofeminine.co.uk the current distribution of the ‘Cowley’ name is as shown in the table below.  This information perhaps     

creates more questions than it answers!  We know that our branch of the family has it’s origins in the Brighton area, at least back in to the mid 18th century but where did they originate - the Isle of Man perhaps? Why did they settle in Brighton?

The quest continues!