In latest version of Electrum (v3.0.2)... Right click on the address tab ("View - Show Addresses" if you can't see the Addresses tab)... select "Details"
You'll see the address, public keys... and the "redeem script"... Copy/Paste that Redeem script into coinb.in "verify":
https://coinb.in/#verifyIt will decode it and show you the addresses that match the public keys.... you will then need to use the original wallets to get the private keys for the addresses.
To create a two out of two wallet, first Electrum creates a normal wallet (containing ordinary addresses), secondly it creates the multi-sig wallet (containing multi-sig addresses).
So to get the priv keys for normal addresses relating to the second wallet (currently containing only multi-sig addresses), I needed to import the seed into another ordinary wallet which then holds all the secondary keys needed.
Thanks for your help.