Over exposure! Rita Ora flashes her knickers as she attends her 70's themed birthday party in a revealing red gown

PUBLISHED: 08:47, 27 November 2013 | UPDATED: 16:18, 27 November 2013

She kicked off her birthday celebrations by posting a sassy shot on Instagram – and it was an equally upfront Rita Ora who attended her 70s themed party on Tuesday evening.

The hit-maker turned 23 on November 26 and she was keen to finish her big day in style with a star-studded party at central London night club The Box.

With a retro theme and a guest list that included Kelly Brook, rapper Eve and current beau Calvin Harris it was never going to be a low-key affair – and so it proved when Rita arrived in a plunging cherry red ensemble.

But while the outfit turned heads, it did so for all the wrong reasons as she inadvertently flashed her white nickers after climbing out of her cab.

Over exposure: Rita inadvertently shows off her underwear as she makes her way towards The Box nightclub to celebrate her 23rd birthday on Tuesday evening

Indeed, the singer was quite a sight as she exited the black cab with stylist pal Kyle De'Volle, her outfit’s generous hood loosely hanging over her bouffant hair.

Its deep neckline afforded waiting photographers a view of her ample cleavage, while the large thigh-length slash gave her the opportunity to show off her toned legs.

Flanked by security guards, Rita quickly sashayed across the pavement in one of her birthday presents – the stylish Christian Louboutin heels she’d proudly showed off on Instagram earlier that day.

Back seat driver: Rita arrives with close pal Kyle De'Volle

Making an exit: Rita climbs from the rear of a black cab after arriving at the central London venue

Making an exit: Rita climbs from the rear of a black cab after arriving at the central London venue

Here we go: Rita makes her way into the blub, where she and boyfriend Calvin Harris partied until 5am

Revealing: The singer's dress featured a wide thigh length slash that showed off both of her toned legs as she made her way towards popular nightclub The Box on Tuesday evening

Let's go: Rita Ora makes her way to The Box nightclub, where she celebrated her 23rd birthday on Tuesday evening

The 70’s theme wasn’t lost on her pals that evening, with many arriving in a range of platform shoes, loon pants and comedy pimp suits.

Indeed, actress Sarah-Jane Crawford in particular won points for her colourful mini-dress and white platform boots – but the memo appeared to be lost on Eve and Kelly Brook, who both arrived in sophisticated black outfits.

Calvin Harris was another guest to eschew the theme, but he atoned by calling into a local 24-hour garage and splashing out on cakes for the photographers gathered outside on the pavement.

Girl in the hood: Rita's outfit came with a distinctive hood that was loosely pulled over her bouffant hair upon her arrival

All eyes on me: Rita was the centre of attention on Tuesday night when she toasted her 23rd birthday with a 70's themed party in Soho, central London

All eyes on me: Rita was the centre of attention on Tuesday night when she toasted her 23rd birthday with a 70's themed party in Soho, central London

Pals: Rota posted this shot on her Instagram account with accompanying caption: 'Studio 54....70's The ORA and Devolle way @kyledevolle #itsmyBirthday'

Girl in the hood: The hit-maker arrived at The Box nightclub in a cherry red ensemble with a hood pulled across her head before pulling it off to reveal a very distinctive bouffant

Here she is: The hit-maker arrived at The Box nightclub in a cherry red ensemble with a hood pulled across her head before pulling it off to reveal a very distinctive bouffant

Flanked: A mixture of friends and security guards accompany the singer as she makes her way to The Box

Quite a sight: Rita stands out in her bright red dress as she steps out to celebrate her 23rd birthday

Him and her: Rita and Calvin pay a visit to Soho for Rita's 23rd birthday

The Scottish DJ would party with Rita - who he started dating earlier this year - until 4:30 in the morning before the bleary looking pair made their way home in the back of a cab.

Writing on Twitter shortly before her party got underway, the singer revealed that all proceeds from the bash would be donated to a cancer charity.

‘I’m using my bday to raise money for @royalmarsden! Give a gift and donate to help cancer patients here,’ she wrote alongside a link to justgiving.com.

On Tuesday morning Rita shared a picture in whi she appears with a large black cushion protecting her modesty as she throws a sultry gaze at the camera.

In a caption that mirrors the words emblazoned across it she writes: ‘Birthday girl!! today I'm allowed to be A F***ING STAR! Thank you everyone for the birthday wishes and I love you!!!! (sic).’

Other guests to attend her party on Tuesday evening included Jaime Winstone and Rizzle Kicks star Jordan Stephens.

Good times: Calvin and Rita have a laugh outside The Box on Tuesday evening

Embracing the theme: Eve (L) and Sarah Jane Crawford (R) are in full 70's mode as they make their way into The Box

Plenty to smile about: The actress and model was stepping out after a busy seven days that saw her open her first restaurant and celebrate her 34th birthday