The best places to buy a bikini in London

Housing a very cool product in a beautiful, gallery-style space, the first flagship store of minimalist brand Prism is a triumph. Sleek swimwear sits alongside beautiful espadrilles and the sunnies that the brand is known for. With a friendly and very helpful assistant, plus a changing room that felt more like the living room of a dream london flat, this was a trauma-free experience. The huge room was flatteringly lit by a reading lamp and from behind the mirror, so you'd have to squint to see any imperfections. The mirror was massive and sneakily tilted (prolific selfie-takers will know that trick), and a robe was provided.

BIKINI BOTTOM LINE: Top marks for lighting, wiggle-room and service at this sleek boutique.

This newly refurbished Monki shop - with silver streamers, glitter balls and a mirrored staircase - has a fun disco feel to it. But the party ends there, with not enough room to swing a sombrero: the try-on space is itsy-bitsy-teeny-weeny! And the staff, though friendly, aren't overly helpful. However, the soft lighting, Pet Shop Boys-heavy playlist and sweet '50s-style bikinis go some way to redeeming the shop. And with prices almost as small as the fitting rooms, it's hard to be too critical of Monki. But it's probably best to pick up a few styles, and then try on its swimwear at home, with room to get a proper look at yourself.

BIKINI BOTTOM LINE: Bargain swimwear served up disco-style, but no room to shake a leg in.

The Oxford Circus New Look was chaos: not conducive to a relaxed shopping experience. Finding my size was an ordeal in itself, as almost all of the swimsuits were on the wrong hangers; however, an assistant did help me sift. The queue for 'backstage' - as they now style their changing rooms - was everlasting; and the star factor goes no further than the label on the door. A relatively roomy space with a decent-sized mirror was ruined by harsh overhead lighting. Despite selling swimwear by cup size, with one of the broadest ranges on the high street, New Look has no fitting service - a real shame.

BIKINI BOTTOM LINE: A D-list experience in a celebrity-themed changing-room area.

There might not be any cocktails or sand, but this one-stop holiday shop has the feel of a resort, with whitewashed wood and music to put you in the mood for Ipanema. Rather than harsh overhead lighting in the spacious changing room, the large mirror is lit from behind, so lumps and bumps aren't too easy to spot. A waffle robe eliminates awkwardness when asking for sizes in the buff, while making the experience feel rather spa-like. Knowledgeable staff and an excellent selection of swimwear in a good range of cup sizes helped make this almost pleasurable. If only that gentle lighting was available on the beach.

BIKINI BOTTOM LINE: Full marks across the board for this beach-babe of a swimwear store.

Good old M&S is well known for its free bra fitting service and its focus on properly-sized underwear. So it's surprising that the swim shop is nowhere near the lingerie. Instead, it's an unmanned island and shoppers are left to go it alone. The experience is more akin to T-shirt shopping, which it shouldn't be - because buying swimwear is essentially buying undies that the whole beach gets to see. The changing rooms are fine: not exactly squeaky-clean, but a decent size and not too bright - good news for a body that's just come out of hibernation. But there's an alarming rear-view mirror that gives you a perspective you never wanted; then again, when it comes to wobbly bits, forewarned is forearmed. Surprisingly for Marks, the assistant was unhelpful when asked about fit and the availability of other sizes, which is off-putting when you're feeling vulnerable and flabby.

BIKINI BOTTOM LINE: You'll need to comfort-eat those famous chocolate souffles after shopping.

Pinker than the Hamley's Barbie department, mirrors everywhere, dimly-lit rooms and a sickly scent of perfume... if a ten-year-old girl were to design a nightclub, this might be it. However, decor aside, shopping at this US import was a very positive experience, largely down to the fact that, as well as their boob-boosting bikinis, the Victoria's Secret team have shipped their all-American customer service over here. This was the only store that offered a fitting service, which happened initially over my shirt on the shop floor (mildly embarassing); but once in the changing room, I was properly fitted for a bra and swimsuit, Bright halogens were compensated for by a big mirror, softly lit by lamps and a little bell to call for friendly assistance. While the branding isn't exactly to my taste, this place impressed.

BIKINI BOTTOM LINE: Superlative Yankee service; yukky pink colour scheme.