Rachel Riley shut down Anne Robinson after the host made a swipe at a Countdown contestant, amid reports of a bitter 'feud' between the stars.

In a recent episode of the Channel 4 gameshow, Rachel, 35 - who is now on maternity leave following the birth of her second child - jumped to the defence of player Stu Harkness after he sold the maths equation.

As Anne, 77, made a dig at Stu's achievement in the pre-recorded episode, maths whizz Rachel was quick to counteract Anne's remarks by congratulating Stu. 

The episode saw Stu's opponent Matty reveal he struggled to get the the answer of 401 from the six numbers on the board.

But a smiley Stu said to Rachel: I’m gonna have a bash at 401.'

As he read out his equation and Rachel wrote out the formula, she said to him: 'Yeah, you knew you had it.'

But former Weakest Link host Anne jumped in, quipping: 'Yeah but he’s a maths teacher, Rachel.'

At this, Rachel - who has a maths degree from Oxford - remarked: 'Still, there’s a lot more pressure.'

Shutting down Anne's jibe, she went on: 'There’s a lot more to maths than just timing numbers together.'

Turning to the contestant, she added: 'It’s a skill - well done, Stu.' 

The awkward moment comes as it's been reported new host Anne is at loggerheads with maths whizz Rachel and lexicographer Susie Dent, 56, with an uncomfortable atmosphere' erupting since she took on the role.   

Speaking on the Lorraine last week just 14 days after giving birth Rachel of her co-star: 'Anne's not the cuddliest person in the world, but it's just a different show now, she's making it her own. 

'She's getting some stuff out of the contestants - sometimes it's barbed, sometimes it's funny, it's just got a different flavour.'

Last month Anne reportedly turned off Rachel's microphone on set after becoming irritated by the host's small talk. 

According to The Sun, Anne became fed up of listening to Rachel chatting to contestants ahead of going on air, turning up at the last minute and being on her phone too much.

Rachel then reportedly told crew that she 'completely disagreed' with being silenced after the incident.  

A source told the publication: 'It's safe to say there's no love lost. Anne is famously known for two things: her dislike of noise and time-keeping. She'll tolerate neither.

'Anne also has tinnitus and cannot bear excess sound. Rachel, with her big heels and even bigger personality, can be quite loud on set. Rachel used to chat to contestants before every show, and Anne found it hugely distracting. 

'She felt she couldn't do her job properly, or bond with the contestants to help them to relax, before the cameras started rolling.

'The tension was palpable. Anne finds the whole thing hilarious.' 

It was reported that Rachel threatened to quit Countdown unless Anne was disciplined for muting her microphone. 

Representatives for Anne, Rachel and Channel 4 were contacted for a comment at the time. 

The reported behind-the-scenes feud between the trio of leading ladies at Countdown has set tongues wagging among fans. 

Rachel has reportedly been supported by the Dictionary Corner star Susie Dent, 56, during the spat.

Staff at Media City studios in Salford claim that off-camera, there's tension over Anne's 'rather grand ways', which have earned her the nickname 'Queen Anne'.

Colleagues also claim Anne who presented her first show in June, 'doesn't mix with anyone' and brings her own stylist and make-up artist to the studios.

Oxford graduate Susie who recently split from her husband of 20 years, Paul Atkins, is understood to be close friends with Rachel who went to the same university.