Byron got its start after its owner, Tom Byng, experienced true, American burger places while he lived in Providence, Rhode Island, and wanted to open one in London. Byron gets its hamburger meat from Scotland, trucked in every morning. It is minced fresh everyday, and is served in a small bun. Unlike other restaurants/pubs where you will find British mince beef, Byron is better tasting and American style.
Having lived in London a long time, and being a true American who enjoys as much American food that I can find here, (including American pancakes and hot dogs), I have to admit that Byron's hamburgers are very good. You can choose from either the Classic, the Byron (dry cure bacon, mature cheddar and Byron sauce), the Chicken, the Veggie, the Cheese, or the Skinny (which comes without a bun). Chips, salad, onion rings, macaroni cheese or coleslaw come at a small extra price, and with two drinks, will make for a very affordable dinner for two for less than £30.
Of course, if you want a cheaper burger, there is always the McDonald's and Burger King alternative. But you get what you pay for. Other burger joints in London fare not much better. Ed's Easy Diner's says it's American style, but I say not really. Most of the burgers in pubs are just OK (but would taste good to anyone who has been drinking), and hamburger meat bought from any of the local high street stores does not come close to American hamburger meat.
For my money (and taste buds), the best hamburger in town is at Balan's Cafe on Old Compton Street in Soho. It is American-style-large, and tastes close enough to American ground beef that if I close my eyes I could swear I was in a diner in Middle America. It comes on a very large bun and tastes like a real, mouth-watering American hamburger. For £10, which includes lots of chips, this very small cafe is a great find in London's West End. There are not that many tables, but if it is full it is worth the wait to taste their succullent and tasty hambugers.
And if you don't want to wait, there are a couple Byron's around the corner whose burgers are a distant second to Balan's Cafe.