I have just built up a 7200s with sip trunks and by default the forwarded cli is from the external caller (in Australia anyway)
But I needed to send the system SIP indial number and was able to do this in 2.6.2 turning Repeat Cli off
So to send system number, Repeat Cli off
To send Incoming caller Cli, Repeat Cli on
So playing around with these setting might help if its possible in the UK in the first place
