Hi Richard,
Sorry you’re having trouble with this! This is unfortunately the result of some security-related code we have that, as you describes, strips and/or escapes HTML of various types before communicating it to/from the database.
Even if HTML is “valid”, it might still get stripped, so the best alternative I can recommend is to just use a filter to achieve the same result – you should fortunately be able to do this quite simply, by using the tribe_events_before_html filter in your theme’s functions.php file.
To see an example of this, I’ve made a Gist for you that you should check out here → http://git.io/vLXlK
If you copy and paste that code into your theme’s functions.php file, it should help here.
Let us know if it does! Or if you have any other questions or concerns 🙂
Thanks,
George