Hi,
I too had previously tried to obtain these and am the person who was told the library may help linking to Mr Dibble.  As Hugo mentioned he sadly died last year.
I was however able to obtain photocopies at a cost as they are not copyrighted.  I believe I got them through the Gwynedd Family History Society Library found at 
www.gwyneddfhs.org.  All my contact was via email as I am in NZ.
There are in fact a total of 4 books.  
Rhiwledyn and the Little Orme  - Library No 668
Penrhynside  - Houses and Families Parts 1 and 2  - Library No not marked but probably 665 or 669
Bodafon and Pant y Wennol  - Library No 667
Nant y Gamar  - Library No 666
They were copied and posted to me.  
Hope this helps