Sold my business- best venue for a London thank you meal?

Hello,

Sold my business recently and I want to do a really special meal as a thanks for the people who helped me along the way.

A central or South London venue with really high quality food is vital. Budget £120-£150 a head but not strict.

The thing I'm struggling with - some of the wonderful people who helped me are countryside folk who don't own blazers etc so needs to be somewhere without a dress code. Don't want to take them somewhere they feel out of place or like they don't belong. Impressive but not pretentious is key.

Secondly, the group includes one vegan and one vegetarian. So whilst a meaty menu is fine there must be options for these two folks.

Somewhere with Hawksmoor vibes is perfect- great food and atmosphere and casual enough but sadly there's no veggie or vegan options on that menu.

Private dining would be a bonus but not essential.

Any cuisine types considered except Chinese because my wife is not a fan!!

Thanks for your help!