Tom Grennan was on the toilet when Calvin Harris contacted him about their collaboration.

The 'By Your Side' hitmaker - whose track with the superstar DJ was released earlier this month - has revealed he was in an awkward situation when he noticed a message asking about teaming up on a song.

He told the 'Celebrity Search Engine' podcast: "I was on the toilet scrolling through Instagram and I went on to my messages and I saw that Calvin Harris has messaged me.

"I was, like, ‘What?’ I rang my manager, still on the loo, and I was, like, ‘Calvin Harris has just messaged me. What should I say?’ And he was, like, ‘Say yes!’

“Then we got on the phone straight away and just had a good old chat.”

Tom had high praise for Calvin, admitting he always wanted to collaborate with him.

He added: "He’s amazing, I always said I’d love to work with Calvin Harris.”

The collaboration with the 'Giant' hitmaker comes after he teamed up with Ella Henderson on 'Let's Go Home Together'.

The track was co-written with James Arthur - who was also originally meant to sing on the track - and Ella had been performing it live years before.

She said: “This song has always been so special to me that I kept going back to it. Tom and I have been friends for years, I love his voice and I’m so happy we got to do this together.”

The 'Oh Please' star commented: "When Ella hit me up and played me this song and then asked me to join her on it, I was absolutely buzzin'. Ella is a good mate of mine and it's so sick to finally get to sing together!"

Meanwhile, the 25-year-old singer-songwriter - who released his chart-topping second studio album, 'Evering Road', in March - recently revealed his dream duet partner is Lady GaGa.

He said: "I would love to work with Lady Gaga. I think she would probably take the hook... she would make it a hit! She's a legend, I love her and her voice is just magical. I would love to work with Gaga and I would love to work with Benny Blanco as well."