ok, I've found the answer and it seems to be a combination of things.

Via Reporting Services Configuration Manager Add an additional HTTP identity for both the web Service URL and Report Manager URL.

Set Host Header Name to localhost

Set TCP Port to 8080

Note, I also found that 80 clashed with Skype causing a 'Page cannot be displayed' error

Although I have amended my Skype setting, I also amended the SSRS port

I'm not sure how crucial this is but it worked for me

Through Control Panel

Search for UAC, select Change User Account Control Settings

Amend to Never Notify

I am uncomfortable with this but have found no other way of getting this to work.

Thanks