Actually on the menu there is:

Secretts Farm asparagus with roasted golden beetroot, pine nuts and leaf salad.
This is marked as vegetarian, as is the seasonal soup, which does change every few days but sometimes that won't be vegan. The breakfast menu also offers soft boiled egg and soldiers. Otherwise that is it.

Strangely a number of items don't have the vegetarian logo, including the fruit platter, the cheese and all of the desserts. The cheese will presumably have a rennin issue. Summer pudding could possibly be vegan but they are offering to serve it with cream or ice cream.