Thanks for taking the time to respond Mike – much appreciated.
Since writing the post, I tried a manual install and that all went according to plan. So, as you say there’s nothing wrong with the plugin.
I also took the matter up with my Hosting Company and they are currently rebuilding Litespeed as they say this could have caused an issue. I suspect that this is the main problem here.
The other point is that this is the first plugin I am updating since WordPress 3.5.2 was installed the other day. Don’t know if that has anything to do with it.
I’ll let you know! By the way, I use the plugin on all my sites, so keep up the good work!
Chris