Gillian Taylforth British Soap Awards 2016
Gillian Taylforth attended the British Soap Awards 2016 at Hackney Empire on 28 May 2016 in London, England. Jeff Spicer/Getty Images

EastEnders star Gillian Taylforth's fiancé David Fairbairn was found unconscious in a gutter after his drink was spiked with date rape drug Rohypnol at the British Soap Awards. Fairbairn, who is currently being treated for cancer, was rushed to hospital after being found unresponsive on the street.

According to The Sun on Sunday, the incident is said to have happened at a bar in East London, while the couple joined the rest of the EastEnders cast for pre-award drinks. According to a source, he was seen "slurring and falling about" shortly afterwards. The source told the tabloid: "It was only much later that a passer-by saw him lying in the street and called police, thinking they'd seen a corpse.

"He [Fairbairn] remembers nothing beyond the bar, where the cast were all drinking in a roped-off VIP area.

"Gillian and David were both absolutely horrified that someone could have done such a vile thing to him."

The source continued by saying that the actress, who plays Kathy Beale in EastEnders, was very embarrased: "David seemed fine at 4pm on Saturday, but not long after that it became clear he wasn't right.

"He was slurring and falling about. When they went on to the Soap Awards, he was a real embarrassment. At the time Gillian was furious. Then he disappeared.

"It was only much later that a passer-by saw him lying in the street and called police, thinking they'd seen a corpse.

"At the hospital, doctors found high levels of Rohypnol in his blood. They said it was a massive dose."

Rohypnol is a tranquiliser that is 10 times more powerful than Valium and is tasteless, odourless and easily dissolves into drinks. It has become notorious as a "date rape drug", as it leaves people partially conscious and compliant for up to six hours, and unable to remember what has occurred in that time.

The Sun reports that police are now checking CCTV of the East London bar where the incident is alleged to have happened.

A spokesman for Fairbairn said: "Dave is unable to comment on this matter. 'However, he would like to make it clear that he does not suspect anyone at EastEnders of doing this, nor can he state where it happened."

Fairbairn and Taylforth met through friends after the breakdown of the actress' 23-year relationship with Geoff Knights in 2009 and have been together for nearly four years. The pair are planning to get married next year.

Former stockbroker Fairbairn was sentenced to 15 years in prison in 2003 after being found guilty of plotting to smuggle in Ecstasy into the UK, after police found 839,500 ecstasy tablets worth an estimated £7.5m ($10.9m). He served seven years of his sentence.

Taylforth returned to EastEnders to reprise the role of Kathy Beale-Mitchell (now Kathy Sullivan) in September 2014, after leaving the show nearly 15 years before.