"Can everyone raise one hand in the air to show that we're together?" asks Katy Brien. The Peckham-born 25-year-old is headlining Liverpool's annual celebration of the lesbian, gay, bisexual and transgender communities, now in its fifth year after being set up in response to the appalling murder of gay teenager Michael Causer. It says much about Liverpool's determination to send out a more positive message that the crowd embraces everyone from a young child decked out in full Dickensian regalia to burly men in boob tubes.

Similarly, Brien's set has something for everybody: edgier dubstep, chart-friendly pop and 90s rave, when Broken Record segues into Baby D's Let Me Be Your Fantasy. A seasoned clubber herself, Brien's best tracks – such as Katy on a Mission, with its evocative lyric, "when we erupt into the room and hear the sub go boom" – are great dance music about great dance music.

In fairness, they're probably more suited to a strobe-lit nightspot than a rainy promenade with flying pigeons. When Katy insists that Liverpool is "one of my favourite places to play, ever", the video camera unfortunately pans to a middle-aged lady looking thoroughly aghast.

However, the big-lunged singer certainly pulls out all the stops to make this special, with leaping dancers, an outfit that could have been made from her auntie Ada's "jungle theme" curtains, requests to "Jump, Liverpool" and even a chap translating lines about (ahem) "highest highs" into sign language for the hard of hearing.

The thumping minimal electro Aaliyah sends sub bass across the Mersey, but there's a special moment when Lights On instantly brings the sun out and everybody cheers – as if the heavens are smiling over what is being done in Michael Causer's memory.

• At Total Access Live, Stoke-on-Trent on 9 August. Then touring. Details: katybofficial.com