Originating from the de Breteuil Norman French

The suggestion is that the name Brettle comes from de Breteuil, a commune in the Oise region of Normandy where Guillaume Fitzosbern, Seneschal to the Duke of Normandy, had his castle, Chateau de Breteuil.  The De Breteuil coat of arms is shown here.

You can read more about the history of the Breteuil family and their chateau here.  Fitzosbern, who fought at the battle of Hastings, was an important and faithful supporter of William the Conqueror, so much so that when King William I returned to France in 1067 he left Guillaume, Lord of Breteuil, and his brother in charge of England in his absence.  William rewarded Guillaume for his service in the conquest of England with the grant of estates in the Isle of Wight and the county of Hereford, whereby he became Earl of Hereford.  You can find more of the history of Guillaume, his origins and descendants here,  here , and here.  Although Guillaume had estates in Herefordshire and Worcestershire he also had major estates in other parts of England but the name Breteuil or its variants does not seem to feature strongly in history after Guillaume’s son, Roger de Breteuil, rebelled against William I (see here), with a result that his lands were forfeited and the earldom discontinued. 

Brettle and its variants seem to appear some centuries later after references to Breteuil had largely disappeared so far as I can see.  For these reasons I find it difficult to explain why Brettell and similar names are concentrated particularly in Staffordshire and Worcestershire if they follow simply as a developing variation of the original widely distributed but dissappeared Breteuil.