Situated at the top of One New Change in the heart of the City is D&D owned bar and restaurant, Madison. I highly recommend a trip here for the spectacular vista over London and some particularly great views of St Paul's Cathedral. With views like these who needs to spend £25 going up the eyesore that is the Shard?
Cocktails at Madison start at £9 - I went for the Pornstar Martini (passionfruit, vanilla vodka and chaser of champagne), which is always a winner despite its embarrassing moniker and the Strawberr'Le (strawberry vodka, limoncello, prosecco) was like summer in a glass. Accessible rooftop bars are few and far between in London, with many only open during the summer months and wiht a massive queue and tiny capacity to boot (Vista at The Trafalgar is guilty of this). Madison can be enjoyed all year round thanks to some cosy blankets and impressive outdoor heating, but there is a glass fronted inside too. Be warned, Thursday and Friday nights are horrendous and you will spend a lifetime at the bar.
I haven't tried the food since D&D took over - I know before that it was distinctly average - so let me know if you have in the comments box below.