How to pronounce River Nene

Albert moored on the River Nene or Nen in 2005
As residents of Northamptonshire we are very aware that the pronunciation of the River Nene varies with locality. In most of Northamptonshire it is usually pronounced Nen (- as in hen) but around Peterborough, and further east, it is pronounced more like its current spelling as Neen (- as in bean). 
Our local BBC TV News (Look East), always careful about the pronunciation of place names, appears to be sensitive to this point. When addressing the “west of the region” they use Nen but use Neen when talking about items that concern Peterborough and Wisbech.
It was with some interest that I found an interesting reference to our local river in a copy of Our Waterways by Urquhart A. Forbes and W. H. R. Ashford. Published in 1906, I recently purchased a copy via ebay. It covers the history of inland navigation as part of water conservancy and has an interesting take on how inland navigation could have been controlled for the greater good - shame it wasn't.

In the book the river is spelt throughout as the River Nen. This adds evidence in support of the of the statement in the Wikipedia entry that the old pronunciation was Nen and that in the 20th century  the pronunciation changed from  Nen and Nene and that the boundary between the two pronunciations began moving inland.  It appears that the current cut-off point is around Thrapston.