Le Pont de la Tour, 36D Shad Thames, London SE1

Nothing on the landscape of London dining so greets the spring as the array of restaurants that lines the Thames at Tower Bridge. When the daffodils are out in Hyde Park, and legs of spring lamb hang in the windows of Allen's and Lidgate's, then (as Chaucer might have put it) folk long to go dining al fresco. For 20 years, the Pont de le Tour has offered City locals and rich tourists a gorgeous view of the river from the terrace. Terence Conran's flagship eaterie started life in 1992. Since then it's been bought by the D&D group (which owns 19 London restaurants, including the Pont's less posh neighbours, the Blueprint Café, the Cantina and Butler's Wharf Chop House) and celebrates its 20th birthday in October. Inspired by the whiff of Easter spring in the air last week, I went to pay my respects.

It's more posh and snooty than I remember but the bar-and-grill area is packed and friendly. A black piano promises later cocktail stylings to go with your asparagus and charcuterie. In the main restaurant, framed ink drawings of aristocrats at play line the walls, the napery is blindingly white, and the clientele unmistakably from Bank rather than Bermondsey. Tim and I sat under the Pont's wide awnings, admiring the silver tubs of greenery, lit by fairy lights, that give the restaurant's frontage a shimmery glow. We liked the views of the City – the red lights like eyes at the top of the Gherkin, the glowing blue of the Lloyds building. A shame, we agreed, that the Shard owners couldn't be arsed to put it in our sight-lines.

The menu was full of classic French dishes – foie gras ballotine, lobster thermidor, veal kidney flambé à la moutarde – interspersed with solid British fare (tian of Dorset crab, Colchester rock oysters) and seemed not exorbitantly priced at £44.50 for three courses. Oyster and caviar dishes carried supplements of between £10 and £95, so I avoided them, while noting that a couple of mains also carried supplements. What the hell, I thought, £2 or £5 extra won't break the bank...

I wish I could rhapsodise and say the food matched the setting, but it didn't. Tim's poached lobster salad was nicely, squidgily chewy with a touch of balsamic and whisper of cucumber, but its 'apple reduction' was over-reduced to vanishing point. My 'scallops baked in a shell' were precisely two scallops, soft, juicy and tender, served with a tiny leek sauce containing, inexplicably, stem ginger. Can we have a rest from cooking scallops with sweet ingredients?

Mains arrived at top speed, as though sent by courier. Tim's Dover sole didn't look the 16oz monster the menu promised. Served off the bone, meunièred (with brown butter, lemon and parsley), it was perfectly OK without being in any way memorable. "It wouldn't surprise me to learn," said Tim, "that it's been sitting under a warmer for half an hour."

My roasted duck breast, over which a Madeira jus was lovingly poured, also lacked that fresh-from-the-pass quality, though the chou farci (Savoy cabbage stuffed with duck bits) made up for it. Tiny new potatoes were a touch underdone, while the leaf spinach was heftily oversalted.

Puddings were urged on us, as though the pastry chef's end of the kitchen was on fire. My griottine crème brûlée was a bog-standard burnt cream in which lurked three maraschino cherries. Finding them was like entering a Spot the Ball contest. Tim enjoyed his 'assiette of English bramble', a plateful of bits: blackberries, bramble jelly, vanilla ice-cream and a delicious, sweet crumble.

Nothing about this meal delivered anything very memorable, apart from the bill. It came to £253. Whaaat? Aghast, I made out the word 'supplement' attached to three of the dishes: the lobster salad, the scallops and the Dover sole. I dug out the menu: bloody hell, yes, the lobster and sole options both carried a faint double-asterisk, indicating they took a £20 (not £2) extra cost, while the one-asterisk scallops carried a £5 supplement.

I have, I'm embarrassed to say, only myself to blame. But when you're inspecting a menu in twilight gloom at 8.30pm, it's hard to see faint asterisks – and who puts a supplement of 20 quid on a main course – and, come to that, on a starter? Are they, ever so slightly, exploiting the confusion of overseas visitors?

I spoke to the waiter. I told him it would be better if, in future, the waiting staff could warn diners they were about to spend £84, rather than £44, on their food. Did he agree? He looked into my face, silently but eloquently asking: "Êtes-vous complètement fou, Monsieur Muppet?"

Go to the Pont for the best summer-evening view in London dinerland. But be prepared to be whizzed through your dinner like ewes through a sheep-dip, to be served slightly tired and formulaic dishes by swishy French waiters, and to get a ghastly shock if you take your eye off the ball at the ordering stage.

Le Pont de la Tour, 36D Shad Thames, London SE1 (020-7403 8403)

£150-£250 for two, for three courses with wine, depending on how hard you're concentrating

Food **
Ambience *****
Service ***

Tipping policy: "Service charge is 12.5 per cent discretionary, of which 100 per cent goes to the staff; all tips go to the staff"

Side orders: On the waterfront

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