Thanks for the help so far.
I have deleted the second outgoing route.
I have no CID in the trunk or the outbound route.
I have set the CID in the ext.
ext 100 01618261804
ext 210 01628261272
If I call my Three mobile number I get the 2 different CIDs however If I dial a Sky mobile number I get an operator message ‘The destination dialled is not supported’
Which I have posted in Syntax for a custom Destination
So one step further.
This sounds like the mobile operator is not ‘happy’ with the caller ID provided. 
Any more avenues to try please.