In my opinion the White House is a prententious bar/club with expensive drinks, a strict door policy (if you're not 'trendy' enough you're not coming in!) We were so disappointed when we heard they were taking over the Mansion as we did not want it to become like the White House.
We went in tonight for the first time to check it out and.....oh dear

Yes, the decor has become various shades of beige (but I'm sure they would call it pale gold!), they have taken a lot of the sofas away and replaced them with much more formal dining room chairs. On the whole there is much less seating than before. The bar staff and chefs did seem to be have teething troubles but it is early days so we'll give them the benefit of the doubt. For a Saturday night it was very quiet and the atmosphere was pretty lacking.
However...the menu was the real disappointment. If you like jus, saffron reductions, quails eggs and black pudding then you'll be very happy! If you like decent pub food - burgers, thai curries etc - then the Mansion is no longer the place for you. There were 6 main courses on offer, only one vegetarian option, prices between £7-£15. They have an extensive wine list with food matching recommendations, but we did wonder if there will be many takers of the Krug for £150!
I know it's early days for them and it will take a while for them to settle in, but we are sad that we seem to have lost a very decent pub and gained a wannabe fancy dining room that also serves drinks.