London's Al Fresco Food Spots

Flanked by the Thames, the dome of The O2 and Canary Wharf, the Martin Brothers have turned The Gun in Docklands into one of the city's finest gastropubs. The huge outdoor terrace offers a great view of the river, making it easy to imagine Lord Nelson having a furtive tryst with Lady Emma Hamilton in years gone by. Every summer, the terrace is converted into A Grelha - a free-standing al fresco restaurant serving Portuguese specialties. The Mediterraneans' passion for grill cooking is demonstrated here right before your eyes. Fish, poultry and steak are all selected by the diner, weighed (to determine the price), then flash-fried or more likely grilled while you wait. There's an extraordinary array of tapas and dipping sauces, freshly baked bread and a specially imported selection of robust Portuguese wine. Yum.

Babylon at the Roof Gardens is hidden on top of the old Derry and Toms (later Biba) department store, one hundred feet above Kensington High Street. This rectangular-shaped restaurant offers amazing views of west London and of the various sections, the Roofterrace, Restaurant and Hanging Gardens are best for al fresco dining. Over 100 trees (all of which are under a preservation order), a stream and garden pond with flamingos and ducks combine to create a magical environment that defies its unique elevation. During the summer they hold barbeques on the terrace - you're more likely to bag a prime outdoor spot at lunchtimes. If you're eating in the evening you have the option of following your meal with a spot of clubbing. The Roof Gardens Private Members' Club is in the same building and Babylon patrons can, at a cover charge, gain access to the club. Surrounding the restaurant are also 1.5 acres of lush rooftop gardens which you're strongly advised to explore before you enjoy your evening meal or after a long languishing lunch. The gardens are divided up into three distinct areas; traditional English, formal Spanish and Tudor. The English garden, with its wild woodland theme, appears the most extraordinary, considering its position on top of an office block. Fountains, vines and palm trees define the Moorish idyll, while the Tudor garden provides a delicate contrast with roses, wisteria, ivy and leafy arches. This really is one of London's secret treasures and guaranteed to whet your appetite before your feast.

Inn the Park is the brainchild of famed restaurateur Oliver Peyton, his idea being to cook up quality alternatives to the soggy sandwiches and warm cola of picnics past and create a new era of 'inn-park' dining. And, it must be said, he's done a remarkable job - simple and seasonal British food is served in a contemporary, no-fuss environment that succeeds in being inviting at the same time. The menu changes through the day from brunch to buffet to cafe to proper restaurant, and there are picnics to take away in summer. The food - especially the buffet - can be a little variable in quality, but it is often excellent. Prices are reasonable, and the location, in the midst of the royal park, overlooking Duck Island and the lake, more than makes up for any complaints. The stroll through this glorious green expanse to reach the restaurant is another high point - if you stop on the bridge you can look one way to see Buckingham Palace and the other for the London Eye standing picture-perfect behind the Foreign Office.

The City of London does many things well, but green space is not one of them. So, when summer strikes the suits roll up their sleeves and head to Le Coq d'Argent. The huge roof terraces at this fabulous French eaterie atop No 1 Poultry makes it the most sought after alfresco spot on the square mile. The menus - an all-day brasserie menu, and a gourmet evening a la carte - are tailored to suit the City's distinctly conservative tastes. Dishes such as traditional Coq au Vin and Sea Bass fillet with ratatouille and shellfish are so scrumptious that they even distract from the fantastic views. It's suitably pricey and there is plenty of caviar for those seeking to impress either a date or client. Another advantage of the rooftop outdoor space is, post smoking ban, this is one place where you can happily puff away without having to loiter around the door downstairs.

From 18th April until 29th September, this riverside cafe commands wonderful views of the Thames from outside the 18th-century Somerset House. Large sunshades shield customers from the sun's reflective glare, while cooling breezes waft in off the river. Order a salad and some fresh fish and watch the boats meander along the river as the sun goes down. Facing away from the bustle on the Strand, overlooking Waterloo Bridge and the Southbank it's easy to forget you're just minutes away from the West End. Formerly the River Terrace Café, the venue was reopened as Tom's Terrace in spring 2010 with Michelin starred chef Tom Aikens at the helm. Despite the excellent setting, critics have been rather savage with Aikens' latest venture, invariably describing the food as simple and overpriced. With burgers costing £14.50, steak sandwiches at £17.50 and a side salad at £4.50, they may have a point.

When a top chef claims to be opening a 'simple', 'low-key' restaurant, it is usually press-speak for some folie de grandeur two doors down from The Ivy with an £85 tasting menu. Petersham Nurseries is the exception. Located in what can only be described as a shed (spacious, light and furnished, but definitely a shed), it's the sort of restaurant where you'll see the chef popping out of the kitchen to pick herbs from the garden, and where homemade lemonade sits above the Pinot Noir on the drinks list. And it's absolutely perfect, especially in summer, when you can sit in the garden. Superb meat and glowingly fresh vegetables peep from beneath mountains of herbs. Of course, all this rustic simplicity doesn't come cheap. Dirt floors, rickety furniture and food bought directly from tiny organic farms all over Europe are ferociously chic and prices are high for a restaurant that is such a long way from anywhere. Still, if you'd prefer a relaxed meal in a lovely location to an army of uniformed staff, then this is the place to go. As a lighter alternative, you can always settled for a cup of tea (from exotic flower teas to the traditional English Breakfast) and a nice slice of cake in the Teahouse.

The Serpentine Bar & Kitchen on the eastern edge of the Serpentine in Hyde Park has been given a facelift and is now run by Ben and Hugo Warner, of Benugo fame. These two have already transformed the restaurant at the BFI and, since taking over this large Hyde Park site in April 2009, they have been bringing their winning formula to the lake side eaterie. Helpfully, the idyllic setting has already been done for them. After a pedallo on the lake or (if you're brave) a swim in the lido which also has a cafe next to it, you can walk around the lake to the Serpentine Bar & Kitchen for meals at any time of day from breakfast to lunch and on to tea and cake. The restaurant's elegantly undulating roof, built in 1965, remains and it's a joy to sit facing the water, watching the ducks which are easily visible through the west-facing wall made entirely of glass.

Perfect for the Clapham Common set, this bar-come-restaurant has a dinky, twinkly garden area which sets it apart from other eateries on this popular stretch. In the summer browse the menu with a little help from the night stars and the glow of some carefully strung fairy lights surrounded by a lovely courtyard. In cooler months a tent-type covering protects diners from the elements, while environmentally un-friendly heaters warm up chilly bones all year round. We've heard good reports about the food and the ambience, which leans towards the romantic, and prices are reasonable. Well worth a visit if you're in the area.

On the first floor of the excellent Lyric theatre in Hammersmith is an elevated oasis overlooking the fountains in Lyric Square. The terrace has blossomed into a roof garden, a welcome addition to soften the Lyric's rather austere seventies concrete block exterior. With food and drinks brought to you from the Brera Cafe downstairs, you can taste their delicious Italian food - panini, pizzas and antipasti - up here among the leaves, trees and greenery. Sip on a cold beer or choose a glass of fine Italian wine and take refuge under the bespoke pergola. It's also reassuring to know that this horticultural haven has been created using environmentally sustainable materials with help from Mark's & Spencer's 5p per plastic bag scheme. Reclining in the summer sun, it's easy to imagine you're far, far away from the hoi polloi of Hammersmith.

When the owners of the popular Waterway restaurant in Little Venice noticed a constant demand for outside tables during the summer months it made sense to open The Summerhouse which offers an additional 60 seats situated directly on the Union Canal a stone's throw from its famous sister restaurant. Open all year round, there's a blue and white striped nautical theme in this establishment, with excellent seafood taking centre stage on the menu. Favourites include good old British fish and chips, swordfish steak, fish pie, mussels and halibut with bearnaise sauce, or transatlantic inspired specials such as New England clam chowder and popcorn shrimps with sweet chilli sauce. There is also a nice range of summery salads. It's not the easiest place to find, tucked away behind a red door and a long wall extending along the bank of the canal, but if you manage to hit off on a sunny Sunday for a waterside meal you'll feel as though you've unearthed a hidden gem. If you've got more than just your lunch hour to spare you can get on board for the boat trip - Jason's Trip run from Little Venice to Camden Lock, ideal for messing about on the river.

From the outdoor terrace at Skylounge, the restaurant on the twelfth floor of the DoubleTree by Hilton Tower of London, you get spectacular views of the Tower Of London, Tower Bridge, the Gherkin, The Shard and the River Thames - which makes this outdoor area a popular place for evening drinks. The DoubleTree is a modern hotel but it's located in an area steeped in history and was built on the site of the medieval Crutched Friars Monastery, Samuel Pepys House and the 18th Century Naval College. The restaurant's terrace, which includes a barbeque area, can get quite busy on Saturday nights as the pre-dinner crowd gather for cocktails with a view.