Belsize Park Fishmonger Bournes: Counter Open 9 am to 6 pm

Bournes runs a fish counter and a small seafood restaurant from the same room at 31 Belsize Lane, Belsize Park, London NW3 5AS. The counter sells fresh fish Tuesday to Saturday from 9 am to 6 pm, and the shop is closed on Sunday and Monday.

Bournes is two businesses sharing one address. In the morning it behaves like a neighbourhood fishmonger, with a display counter of British fish and shellfish. From noon it serves lunch, Tuesday to Saturday from 12 to 3 pm, and on Wednesday to Saturday it reopens for dinner from 6 to 9:30 pm, when the room turns into a candlelit bistro. A downstairs lounge opens for dinner on Thursday, Friday and Saturday evenings.

That arrangement is the main reason to choose Bournes over a plain fish shop. You can taste how the kitchen cooks a fish at lunch, then buy the same species from the counter to cook at home. Diners on OpenTable describe the place as cosy and charming, praise the fish broth and the Portuguese broth, and mention live music on some nights, which tells you the evening is more relaxed than formal.

The website is precise about where the fish comes from. Bournes sources daily from Newlyn and Looe in Cornwall, Brixham in Devon, Peterhead and Loch Duart in Scotland, and Billingsgate Market in London. Those names cover the main English West Country harbours, Scotland's biggest whitefish port and a well-known Scottish salmon farm, so the counter leans firmly on British waters.

In practice that suggests what to look for. Cornish and Devon boats land flatfish such as plaice, lemon sole and turbot, along with crab and scallops, while Peterhead is known for cod, haddock and other North Sea whitefish. Loch Duart supplies salmon. Ask which harbour each fish on the slab came from, since the staff can tell you and it often explains the price difference between two fish that look alike.

Beyond whole fish and fillets, Bournes sells shop-made products throughout the year. The website lists fish cakes, gravlax, fish stock, pâtés and sauces. These are what make a quick dinner possible on a weeknight: a pot of stock turns a few fillets into a soup, gravlax needs nothing but bread and a squeeze of lemon, and fish cakes go straight into a pan.

The stock is the quiet bargain here. Most home cooks never make fish stock because they do not have the bones, and a fishmonger that also runs a kitchen does. Buy a tub alongside your fish if you are making a risotto, a chowder or a bouillabaisse-style stew, and you will taste the difference immediately.

A judgment worth stating plainly: skip the counter on a Wednesday afternoon if you want a long chat about your purchase, because lunch service runs until 3 pm and the kitchen is preparing for dinner soon after. Late morning on a Tuesday or Thursday, before the lunch crowd arrives, is the calmer window.

Flatfish from Cornish and Devon boats are the easiest thing on the counter to cook well. A whole plaice or lemon sole needs only a hot oven, butter and fifteen minutes or so, depending on size, and the bones lift away cleanly once it is done. Ask the fishmonger to trim the fins and remove the dark skin if you prefer, and keep the white skin on to protect the flesh.

Scottish salmon and North Sea cod reward a different approach. Thick fillets do best seared skin side down in a heavy pan, then finished in the oven so the centre stays moist. If you are buying for a dinner party, ask for portions of equal thickness rather than equal weight, because even thickness is what makes every plate cook at the same speed.

That is worth doing for anything large or specific, such as a whole sea bass for six, a dressed crab or a quantity of shellfish for a party. Give a day's notice where you can, say exactly how you want it prepared, and collect it during counter hours.

The website also sells fish and chips to take away for collection, ordered by phone. The days and times are published in two slightly different versions on different pages, so ring the shop to agree a pick-up time when you order rather than turning up on spec.

Belsize Lane is a residential street of brick terraces and small shops with a village feel. The lunch trade includes neighbours meeting for a plate of fish, while the evening draws couples and small groups, judging by the way reviewers write about the cosy room and the friendly staff.

Behave like a regular even on a first visit. Ask what came in that morning, accept a recommendation, and come back the next week to say how it turned out. Shops like this reward the customer who returns.

The lane sits in the knot of streets around Belsize Village, a short walk from Belsize Park Underground station on the Northern line. It is an easy place to combine with a walk: head south through the residential streets towards Primrose Hill for the view over central London, or north up towards Hampstead and the Heath.

If you are coming for dinner, take the walk before you eat. On a fish-buying trip, do it the other way round: walk first, buy the fish last and go straight home, especially on a warm day.

Address: Bournes, 31 Belsize Lane, Belsize Park, London NW3 5AS. Fish counter: Tuesday to Saturday 9 am to 6 pm. Lunch: Tuesday to Saturday 12 to 3 pm. Dinner: Wednesday to Saturday 6 to 9:30 pm. Email: Bournesfish@gmail.com. Reservations can be made online or by phone, with any special requests noted at the time of booking.

Ask the Karpo APP to plan a Belsize Park evening with a walk over Primrose Hill before a Thursday dinner downstairs at Bournes.