Sorry a2ztechnologies, I had temporarily reverted back to the previous version installed. This also gets around the issue, but means I can’t use the latest version of WordPress.
I have upgraded again to the latest version (4.2.2) and… the same problem exists. Screenshot viewable at: files.c-harding.com/public/Screen%20Shot%202015-06-06%20at%2011.18.18.png.
The CMS login is working (e.g. can login, make changes), it’s the Updates section which does not load and is inaccessible.
Appreciate any help and ideas as is a strange issues that may stop me permanently upgrading unless I can resolve it.