Osteria Dell'Angolo, 47 Marsham Street, London, SW1

Glancing around on a Monday lunchtime at Osteria Dell'Angolo, a posh Italian in Westminster, the outlook is pretty bleak. It's about a third full, which must be below break-even, given the location and number of staff. Will it be around this time next year?

To be fair, few high-end restaurants in the Westminster Village are full at the moment. The majority of MPs are out of town, either on the campaign trail or canvassing in their constituencies. Not that they'd be footing the bill in any case – their expenses have never stretched to expensive lunches, even during the golden era. That would be where journalists come in. But we've been feeling the pinch.

Luckily for people such as Claudio Pulze, who owns Osteria Dell'Angolo along with the nearby Al Duca, hope is at hand. If the Conservatives win the election, Cameron has pledged to end all dining subsidies within the Palace of Westminster. That means Harris's, the greasy spoon in between the House of Commons and the House of Lords, will be charging full price for a full English, while The Adjournment, the upmarket restaurant within Portcullis House reserved for MPs and their guests, won't be much cheaper than Shepherd's. For the restaurants dotted around Westminster, happy days will be here again.

Osteria Dell'Angolo opened in February last year and, after an initial hiccup in which head chef Michele Brogi departed, has established itself as a "power restaurant". Pulze certainly has plenty of experience when it comes to fine dining. His previous successes include Canteen, Aubergine and Zafferano and among the head chefs who have worked for him are Marcus Wareing, Giorgio Locatelli and Gordon Ramsay. Not bad for a man who started his career as a bellboy.

The interior looks expensive, as befits a bolthole for Britain's political elite. It's all dark wood and soft lighting, with plenty of booths tucked out of sight for the discreet exchange of plain brown envelopes. For those plotting leadership coups, there is even a private dining-room.

I've arranged to meet Rachel Wolf, the founder of the New Schools Network, and James Marshall, a House of Commons researcher, to discuss my plans to set up Britain's first "free school". They both seem pleasantly surprised that I'm taking them to such a grand restaurant. We set about ordering with enthusiasm, all cross-referencing to make sure we're having different things.

After five minutes, a waiter appears and plonks down a tiny morsel of unidentifiable meat. For a second I think this is my first course – roast quail wrapped with pancetta – but it turns out to be the amuse-bouche. Phew! When the quail finally arrives, it is packed with flavour and it isn't long before I've abandoned my knife and fork to tear at it with my teeth. James is fairly pleased with his chickpea and cuttlefish soup – "fish a bit rubbery, though" – while Rachel thinks her octopus carpaccio is "overdressed".

For my main, I opt for fillet of beef with sautéed spinach and a timbale of potato, ham and leeks, while James has risotto with artichokes and pecorino cheese, and Rachel has squid-ink tagliolini with courgettes and scallops.

My beef is perfectly cooked, but the reduction accompanying it is a little metallic, and the timbale is wafer-thin. Rachel praises her scallops – "delicious" – and James declares his risotto "spot-on", but all three of us are not quite as blown away as we'd been expecting.

For pudding, we share a chocolate tortino with vanilla sauce and almond crumble which, judging from the speed with which it disappears, we all like a good deal.

I have to confess to being a little disappointed, given the size of Pulze's reputation. The new chef, Massimiliano Vezzi, isn't quite firing on all cylinders, not paying as much attention to dressings and sauces as he should. The service is below par, too, with members of staff milling about at the rear of the restaurant, seemingly oblivious to the needs of their customers. It took me 10 minutes to get the bill.

I've no doubt Osteria Dell'Angolo will survive, but it has to raise its game to give the Cinnamon Club a run for its money. Unless things improve, it will be that upmarket Indian that benefits from Cameron's clampdown, not this upmarket Italian. n

12/20

Scores: 1-9 stay home and cook, 10-11 needs help, 12 ok, 13 pleasant enough, 14 good, 15 very good, 16 capable of greatness, 17 special, can't wait to go back, 18 highly honourable, 19 unique and memorable, 20 as good as it gets

Osteria Dell'Angolo 47 Marsham Street, London SW1, tel: 020 3268 1077 Lunch, Mon-Fri, dinner Mon-Sat. Lunch for three, including service, about £100

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Reviews extracted from 'Harden's London and UK Restaurant Guides 2010'. www.hardens.com