Ed Sheeran’s hit song Shape Of You was created from scratch at “extraordinary speed”, co-writer Steve Mac has told the High Court, joking that the songwriting session was so intense it left him with a “headache”.

Real name Steven McCutcheon, the producer is the latest person to give evidence to a copyright trial over the “Oh I” hook in the 2017 song, following Sheeran and third co-writer Johnny McDaid.

Two songwriters, Sami Chokri and Ross O’Donoghue, allege Shape Of You, written in October 2016, copies parts of their 2015 track Oh Why, saying the hook is “strikingly similar” and is unlikely to have been created without “preconceived ideas”.

Sheeran, McCutcheon and McDaid all deny ripping off the song.

In the witness box on Thursday, McCutcheon – who has worked with artists including Boyzone, Westlife, JLS, Clean Bandit, Pink and Bastille – told the court the case was “not about money” but “to clear my name”, echoing earlier evidence from Sheeran and McDaid.

Court told how Shape Of You was created

Telling the court about working with Sheeran on Shape Of You, he said: “I had a headache at the end of the day… it was the first time I had written with anyone like this. It was incredible.”

One explanation for the recording session being so successful was that Sheeran was “unlike any musician you ever worked with”, said Andrew Sutcliffe QC, representing Chokri and O’Donoghue.

However, he also offered an alternative – that the singer had “already worked out how he wanted this song to sound” and “already had lyrics and ideas which he was able to deploy at speed”.

McCutcheon disagreed, telling the court that the “speed that [Sheeran] writes is extraordinary to the point that we can write 26 songs in a week”.

In his written witness statement, the producer described creating Shape Of You at his Rokstone Studios in west London as a “rapid process” and said he had a “clear recollection” that the trio created it “from scratch”.

McCutcheon told the court that he initially supplied the marimba sound on the track and was also “chipping in with lyrics and melody on the day”. He dismissed a suggestion that Sheeran led the session, saying they all contributed equally.

Work on Liam Payne’s Strip That Down – and why it was cleared

Like Sheeran, McCutcheon said he had not heard the song Oh Why before the litigation and had no reason to believe any element of it was copied in Shape Of You.

In his written witness statement, McCutcheon noted a previous occasion when he had sought clearance for a song – Liam Payne’s Strip That Down, co-written by him and Sheeran, due to a similarity with Shaggy’s It Wasn’t Me.

The court has previously been told clearance was sought over a subsequently changed reference to TLC song No Scrubs on Shape Of You.

In his written statement, McCutcheon “strongly” disagreed with any suggestion that the two instances might show he had “a habit of plagiarising other writers”.

He wrote: “I always strive to create totally original songs unless I feel, in a particular case, that it would enhance a song to use a reference to another work.

“If I do so, I give credit where credit is due and inform my publisher so that clearance can be arranged. There is nothing wrong with referencing other songs in that way if clearance is obtained.”

As an “internationally successful writer of many years’ standing” it would be “totally unacceptable” to copy others’ work, he said, “and I would not have achieved the success I have if I did so”.

Sheeran and his co-writers began legal proceedings in May 2018, asking the High Court to declare they had not infringed Chokri and O’Donoghue’s copyright.

In July 2018, Chokri and O’Donoghue issued their own claim for “copyright infringement, damages and an account of profits in relation to the alleged infringement”.

The trial before Mr Justice Zacaroli continues and is expected to last about three weeks.