DP and I visit London occasionally (we are very much country folk!) but tend to be so busy with various activities that we just stop and grab a quick bite to eat, so we don't really know any 'nice' restaurants.
We've got a trip planned for next March (covid permitting!) and will be going with my mum and my foster brother; it will be his 18th birthday so we'd like to treat him to a nice meal out (he's not NT and doesn't do anything on his own, so he won't have any other plans or friends to celebrate the day with).
I have no idea where to start looking though!! DP and I are big meat eaters, both my mum and foster brother don't eat a lot of meat but aren't vegetarian IYSWIM. Neither are overly keen on red meat, whereas steak is one of my main food groups 
We don't want anything overly fancy, I'm just thinking a nice place that does posh pub grub type food? Sort of thinking somewhere that does starters up to £15ish, mains up to £30ish.
We're going to be at The Shard in the afternoon, so somewhere sort of close to that would be good, but it's not essential as we can always get the tube.
If any Londoners, or people who go to London a lot more often than I do 
, can give me some ideas, I would be eternally grateful!!