Duncan James’ partner Rodrigo Reis was put to the test when quizzed on whether Blue is his favourite boyband… and unfortunately for him, a ‘lie detector test’ revealed all.

There comes a time in (some) relationships when all that stands between the truth and some fibs is a scientifically-sound polygraph, ready to examine whether or not two partners can be honest with each other.

In a new episode of Jon Richardson and Lucy Beaumont’s Channel 4 programme Jon & Lucy’s Odd Couples, Duncan – who found fame as one of the members of quartet Blue – willingly put his relationship with his partner under the spotlight.

In an exclusive clip shared by Metro.co.uk, the couple sat at a table across from one another as Rodrigo, who works as a flight attendant, was hooked up to the polygraph, which is often referred to as a lie detector test.

Duncan immediately got down to the nitty gritty, asking his beau, who was making his first TV appearance: ‘Is Blue your favourite boyband?’

‘Yes,’ Rodrigo answered… but the polygraph claimed otherwise, as the device began moving in a rapid manner.

The singer kept on questioning until he had the truth (Picture: Channel 4)

Knowing that something wasn’t quite right, an unconvinced Duncan pressed his boyfriend further as he said: ‘Who’s your favourite boyband Rodrigo?’

‘It’s Blue, Blue is my favourite,’ Rodrigo insisted, before finally relenting… and admitting it was actually the Backstreet Boys.

Later on the programme, when Duncan and Rodrigo were in the studio with Jon, Lucy and fellow guests Sara Pascoe and Steen Raskopoulos, the results of the polygraph test were assessed in further detail.

‘Backstreet’s back alright. It’s not alright, is it? How did that make you feel?’ Jon asked Duncan directly.

Duncan even admitted the Backstreet Boys ‘had better hits’ (Picture: Channel 4)

Nonetheless, the All Rise and One Love singer was a good sport, responding: ‘To be fair, they did have better hits than us really.’

He then turned back to Rodrigo, wanting to know whether he does like any songs in Blue’s repertoire.

‘Yes I do, I do,’ he replied, and when asked which one is his favourite, he ambiguously responded: ‘The new ones.’

Well played Rodrigo, well played.

The couple have been together for several years (Picture: Rachel Joseph/Channel 4)

When it was Duncan’s turn to be appraised by the polygraph, Rodrigo asked him whether he found his Brazilian accent sexy.

‘Yes,’ the musician answered, before admitting: ‘I do. I don’t understand you all the time.’

In October last year, Duncan, 44, paid tribute to his relationship with Rodrigo, reflecting on when they met for the first time.

‘A little throw back with my papi @mrrodrigoreis from the amazing @tropikalifestival – it’s been 4 years since we first met OFFICIALLY and I’m so happy ur my amor. Love u papito,’ he wrote in the caption to his Instagram video.

Rodrigo wrote in the comment section: ‘I’m happy and blessed to have you as partner. May god keep us together; foreveeer, TEAMO papi.’

Jon & Lucy’s Odd Couples airs tonight at 9pm on Channel 4.

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The truth came spilling out!