Starting life as an amalgam of popular message boards covering burning topics of the late 1990s such as cable TV and DVDs, Digital Spy is a survivor of the first wave of UK dotcom startups. James Welsh, who co-founded the site while at school and is still yet to hit 30, now finds himself having to evolve Digital Spy in the face of a new range of competitors such as Buzzfeed and Mashable.

Digital Spy is having a good year: monthly users have hit 24 million, up 30% year-on-year, which in turn has fuelled advertising growth that will see revenues up by a fifth over 2012. Yet figuring out exactly where the entertainment and technology website fits in the new digital era of social media and mobile content consumption is a tricky task.

"Different people have had different points of view as to what we are," says New York-based Welsh, digital technology director for Digital Spy and owner Hearst UK. "To some people we're a soap spoiler site. To others we are the source of the latest showbusiness news. To others we are a great site about TV. I think it is a big site that nobody has heard of but people will be using it."

Hearst, the magazine publisher which inherited the site in 2011 when it bought Elle owner Hachette Filipacchi, is clearly concerned about this profile issue, pointing out the audience is "equal to Mashable" in size and highlighting that it is a "Great British Success Story". Digital Spy was once located in an office above an Indian restaurant across from London's Waterloo station.

"When I look at Buzzfeed [and] Mashable these sites have done extremely well, they are putting distinctive product out there and there is a massive audience for it," says Welsh. "I don't think we need to ape them. We are [also] putting a distinctive product out there and there is a massive audience for it. I genuinely don't think there are competitors to us in that sort of entertainment-through-technology space."

Welsh is aware of the legacy of a slightly scattergun editorial strategy and says that in the last year Digital Spy has hit a growth surge, an "inflection point", by refining its content offering.

"I think we've become much more mainstream in the best possible sense," he says. "Over the last few months we've started unifying our coverage around the idea of the connected home, the connected lifestyle. There is a much clearer idea about what we are about. Whether it is The X Factor, Doctor Who, the latest releases in music or the release of the Xbox One, it's one continuum of coverage about entertainment."

A look at Digital Spy's five most popular pieces of content over the last year (Welsh says the site publishes about 200 articles a day) gives a flavour of this end-to-end entertainment editorial philosophy. A story on the rumoured line-up for ITV's I'm A Celebrity ranks alongside a guide to Apple's iOS 7 operating system, a review of Samsung versus Sony versus LG smart TVs, a news story on Superman: Man of Steel's opening weekend box office takings and a video clip of Huey Morgan storming off Never Mind The Buzzcocks.

"We are the one site [readers] can come to find out what TV shows are worth watching, what services they are available on and ultimately what the best box to put under their TV is that enables their kids to play games and them to watch shows on Netflix and to build their entertainment lifestyle," summarises Welsh.

Research company IHS estimates that 70% of Digital Spy's users are in the UK, although it also has US and Australian versions of the site, with 20% in North America and 10% from elsewhere. Hearst will not reveal financial figures for the business, but IHS estimates revenues this year to be £8m-£9m.

"They have invested in mobile and video technology and partnerships to drive traffic through from other sites and it is paying off," says Daniel Knapp, director of advertising research at IHS.

Welsh says that mobile now accounts for more than 50% of usage, and in the last six months that has been rising by a percentage point a month, with tablets at about 10%.

Traffic and revenue may be growing, but Knapp believes that the biggest problem facing Digital Spy is its relative lack of profile. "I don't yet see it as a great success story because one component is missing: a strong brand name," he says. "It has revenue and traffic but not the brand equity of a Gawker or Buzzfeed. The logo looks outdated, 10 years old."

So it is perhaps no coincidence that 29-year old Welsh, who has previously kept a much lower profile than Buzzfeed's Jonah Peretti and Mashable's Pete Cashmore and says he has never given interviews, is now out promoting his business.

Welsh says he will "happily advocate" for Digital Spy whenever he gets the chance, but the focus is on the 40 staff (20 full-time in London and 20 part-timers here and in the US) and getting the experience right for users. Digital Spy is about to unveil a major design overhaul, with Welsh admitting that the old-style site can be "quite hard on the eye" and is "starting to jar".

"It is the first time we have gone for a major new look, a new logo, it currently looks like an older site, not reflective of content or the frequency, loyalty and scale of the users we have."

Welsh is the last of the founders to stick with the business and he remains invigorated not least because his work on Digital Spy is being used to help Hearst create a digital future for its 19 UK titles, which span Good Housekeeping and Elle to Men's Health and Harper's Bazaar.

"This is a business in transition but it is less about the technology itself," he says. "It is more about the culture that goes around it. I think it's achieving cultural and behavioural change using technology as an enabler. That's one of the reasons why I'm still here, I love doing that."

• This article was amended on 2 December 2013. An earlier version said Digital Spy began in an office above a restaurant near London's Waterloo station. The occupation of the Waterloo office came later, not at the outset of the venture.