My best mate at school was called Mainwaring and it was pronouced as it is written Main - Wearing but ive seen (or heard) the same spelling pronounced Mannering.
Odd!
the only rule for place names and surnames is the way they've become spoken over the centuries. Sometimes the W survives, sometimes not. I suppose it depends on how much local people tend to slur their speech.
We have lots of places here in Norfolk which are pronounced otherwise.
Happisborough...Haysbrr.
Wymondham......Windem
And the worst one of of all which holidaymakers insist on calling Acklee..Acle..pronounounced Achel as in to ache.
Another one is Stiffkey ,village of the infamous vicar,which is pronounced Stewkey.
.
What are you picking on me for searchme?
Have i done something to upset?
I do, however, concede to your implication as i am in fact a massive 'silent W as in anchor'.