M Threadneedle Street

M sits in a windowless, vaulted space beneath the City, a few steps from Bank and the old Stock Exchange, and it was built for the kind of dinner where a deal gets done. Restaurateur Martin Williams, the former managing director of Gaucho, opened the M Restaurants group in 2014 and made this Threadneedle Street room its flagship. The concept is a tour of the world in six steaks, and the wine list runs to more than 120 labels available by the glass.

The kitchen sources prime cuts from six beef cultures — South African rib-eye, French Charolais, Australian grass-fed, Argentine, American and a high-grade Japanese Kobe fillet — and grills them over a high-heat broiler. A 200g Australian Wagyu sits near the top of the card at about £75; most steaks land between £20 and £45 before sides. Beyond the grill there is a raw bar, a sushi counter and a separate wine bar, so a table can graze before the beef arrives.

The room is dark, clubby and quiet enough to talk numbers, split between the main M Grill, a private dining suite and the bar. Service is polished and used to expense-account dinners and after-work City crowds. It runs a bottomless brunch at £55 on weekends, but the restaurant earns its keep Monday to Friday, when the surrounding banks empty out at seven.

The reasons M works for closing a deal are practical. The room is private and quiet, the wine list is deep enough to flatter a guest who knows wine, and the six-steak format gives a table something to talk about that is not the contract. Book the private dining room if the conversation is sensitive. The bill is high, but it reads as seriousness rather than excess to most City clients.

For impressing clients, M trades on location and theatre. It is a two-minute walk from most City banks, the broiler turns out steak that holds up against any London grill room, and a sommelier can run a flight from the by-the-glass list without anyone reaching for a bottle price. Start at the wine bar for a drink, then move to a grill table. It signals budget and competence without tipping into a stunt.

Not for vegetarians or a light meal — this is a beef-first room and the menu leans hard on the grill. Skip it on a Sunday, when the City is dead and the restaurant keeps shorter hours, and avoid it if you want daylight, since the dining room has no windows.

Is M Threadneedle Street worth it? For a City steak dinner, yes. The beef is genuinely good across six origins, the by-the-glass wine list is one of London's deepest, and the private rooms suit business. It is expensive and beef-focused, so it is less suited to a casual night or a mixed group of light eaters. Go when you want to impress a client or close a deal.

What should I order at M Threadneedle Street? Order across the six-steak flight if you are sharing, or pick one origin — the South African rib-eye and the Japanese Kobe fillet are the talking points. Start with something from the raw bar or sushi counter, and let the sommelier pour from the 120-plus wines by the glass rather than committing to a bottle. Sides are charged separately.

How much does M Threadneedle Street cost? Steaks run from about £20 to £75 for the 200g Australian Wagyu, with sides on top, so a full dinner with wine usually lands well into three figures per person. The weekend bottomless brunch is £55 for two courses and free-flowing drinks, which is the cheaper way to see the room.

Where is M Threadneedle Street? It is at 60 Threadneedle Street in the City of London, EC2R 8HP, a short walk from Bank station and the old Stock Exchange. The dining room is below street level, so look for the entrance rather than a window display. It is closed on Sundays and busiest on weekday evenings.