Organised by uncle Ian (and Andrew), the place to be was called Corby.
For those of us who weren't there, the internet does offer some impressions.
Here's Andrew's review:
The first band was called Gumbo Variation and they included a number of Zappa compositions in their setlist.
Picture by Steffen Schindler.
2013/03/08 Gumbo Variation - concert Corby UK
James Burns - guitar * Ollie Snell - guitar * Robin Breeze - bass * Joe Burns - drums
* setlistIntroductions, Grand Wazoo (Frank Zappa), Untitled, Aravalli Wood, Et Alias, Untitled, Untitled, Peaches En Regalia (Frank Zappa), To The Sun, Django
Data has been added to the United Mutations Archives.
An audio recording is up at Zappateers.
And here are some YouTube snippets by Luuk