Hey Cliff,
I have found out the cause – the title was inserted by YEOST SEO plug in.
Events is a custom post type and YEOST generated a default page title of
%%cust_post_prul%% Arvice %% page %% sitename%%
Which kinda makes sense – that event page is an achive vie of the custom post type ‘event’
But in my case I wanted it to say What’s On, so I just changed it.
You may want to make a note of this finding so if any other users ask the question you can suggest they check YEOST.