On the LER the 1st Column has R, RW or NM, and the second column O, OW, DW or a dash.
My grandfahere entry has a a preceding his name and some other entries has a J after heir name.
I would be graeful if someone could let me know how to interpret the notation
ID:6387
* London Electoral Roll
London Electoral Roll
The abbreviations are normally explained at the front of the roll. If you're using something like Ancestry, it will be a few scans in after the scanner's notes and book covers etc.
I think the W denotes Wife
Here's one from 1927 Lambeth

I think the W denotes Wife
Here's one from 1927 Lambeth