'I went to the London pizza bus with Christmas igloos and tasted its mashed potato pizza'

Bus restaurants! I remember seeing one on my first visit to the South Bank - a candy floss store on a giant yellow bus - and it seemed to smack me in the eye as the most out-there thing I'd seen in London. That was well over ten years ago, but the idea is still a novelty.

Heroica Lounge, a pizza restaurant, is the most recent outlet to base itself out of a converted double-decker bus, in this case parked in the Docklands, near the ExCel exhibition centre and facing The O2 Arena on the other side of the Thames. Of course, I had to go.

Visually, there's lots to love. As I stroll along the docklands, the converted red double decker stands out, perched next to a coffee kiosk and surrounded by a picket fence. The bus houses the kitchen and waiting staff, while outside are garden tables and two giant glass igloos - each with four small dining tables inside and chairs lined with white, furry yeti cushions. Inside the igloo I go!

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It's a pleasant, Christmassy dining experience and the service is very friendly with a smile. It's a small restaurant, I count 12 tables in all, but it does also have a top deck terrace on the bus with views out over the Thames. And sitting inside the enclave of the igloo feels quite magical. But what of the menu? What pizza dishes does this London vehicle offer?

For starters, we have Melanzane Alla Parmigiana (£8) made up of tomato sauce, aubergine, mozzarella and parmesan with olive oil and sliced bread; Burrata (£9) served with rocket salad, cherry tomatoes, olives and pizza bread; Garlic Bread (£7) and Bruschetta (£8) with pizza bread, oregano, garlic and basil, olive oil and cherry tomatoes.

There are eight vegetarian pizzas, all measuring 12 inches, including Bufalina (£15) tomato sauce, buffalo mozzarella, parmesan cheese, olive oil and basil; Vegan Meatball (£17) tomato sauce, vegan mozzarella, mix peppers, vegan meatballs, basil and olive oil; and a Filetto (£13) mozzarella, cherry tomatoes, parmesan cheese and basil.

On to meat pizzas and here we have most of our main courses, with 13 to choose from all measuring 12 inches. There's Meatballs (£15) tomato sauce, mozzarella, aubergine, parma ham, buffalo mozzarella and basil; Pumpkin (£15) a pumpkin base instead of tomato sauce, with mozzarella, gorgonzola cheese, pecorino cheese, basil and nduja sausage; and also Friarelli (£15) smoked cheese with friarelli (otherwise called rapini, a green leafed vegetable), Italian sausage, parmesan cheese and olive oil.

I'm about to choose Friarelli when another menu item catches my eye. Mashed Potatoes (£15) a mashed potato base instead of tomato sauce, served with sausage, mozzarella, basil and parmesan cheese.

Can this pizza really just be mash? Perhaps the base will be an inch thick of creamy mashed potato fried over and the sausage will be like a casserole on top, with some caramelised onion and chives and lots of pepper seasoning... it's this curiosity which makes me order it, and I sit and wonder while I wait.

It's served very quickly. A generous-sized pizza, cooked nicely to standard - but one look over the toppings and alas, my imaginings are not meant to be. To put it politely, the mashed potato appears as splodges of yellow paste dotted around hither and thither. The distribution of Italian sausage is ungenerous, maybe one or two small pieces on each slice. And that's it. Essentially it's a bare cheese pizza.

When a restaurant offers an unconventional choice, something you associate with a different kind of meal, you expect something creative. Like bread and butter pudding is more than just slices of bread, or the way the fabulous Yorkshire Pudding Burrito squeezes a Sunday dinner into a Mexican wrap. But unfortunately, this particular dish really is just what it says on the tin.

I gobble up my wholesome lunch and it certainly is filling, if entirely taste-free. The surroundings and atmosphere of Heroica Lounge are wonderful - the river, fairly lights, igloos and a part of London that still has an edgy feel all make for a pleasant dining experience. I just hope the creativity of the décor is matched on the rest of the menu...

Editor's note: The Bufalina is a fool-proof choice at Heroica. Even though they let my brilliant writer down with their mashed potato creation, they do the classics extremely well.

Heroica Lounge is based at Royal Victoria Dock, Western Gateway, London.

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