From California to Hub8: How a Viral Post Sparked Cheltenham’s Transatlantic Tech Challenger

When a Californian tech veteran saw a viral post by an Australian digital marketer at Hub8, it set off an unlikely chain reaction. Sitting just two rows away was an Oxford-educated McLaren engineer. Now hiring UK graduates alongside California based talent, the international team behind Nimbus is taking on workplace giant Slack.

CHELTENHAM — On an ordinary weekday inside Hub8, the co-working space in the heart of Cheltenham’s tech district, Australian-born marketer Zac Radbone was head-down growing his digital agency, Rad.Digital. Then his LinkedIn inbox pinged with an unexpected message from California.

On the other end was Jeff Corliss. Based on the US West Coast, Jeff is a seasoned California based technologist who built his first computer at eight years old, won the California State Science Fair at 13 with the competition’s first-ever website entry, and went on to architect enterprise systems for global powerhouses including Amazon, Oracle, Nike, Disney, and DreamWorks before founding his own venture-backed startups.

Jeff, who readily admits sales and marketing aren’t his natural forte, had grown weary of superficial Californian networking circles. Drawn to the UK through his British heritage, he had been casting his eye across the Atlantic when one of Zac’s candid posts on digital growth exploded, surpassing a million impressions.

“It was completely surreal,” recalls Zac, now Co-Founder and Chief Commercial Officer (CCO) of Nimbus. “I had a post hit over a million views, and out of nowhere this California based heavyweight reaches out to pitch his vision for how AI should actually function in business. Looking at Jeff’s track record, I just thought to myself: whatever this guy is building, I want in.”

Recognising they needed an executive who could bridge deep engineering with commercial scale, Zac didn’t have to look far. Sitting just a couple of rows apart from him on the Hub8 co-working floor was James Campbell — an Oxford University engineering graduate, former McLaren and Dyson engineer, and founder of technology venture Growm. In a real testament to the collision-rich environment Hub8 works hard to foster, a quick conversation across the desks cemented the final piece of the puzzle. James came on board as Co-Founder and Chief Executive Officer (CEO), with Jeff serving as Co-Founder and Chief Technology Officer (CTO).

“He speaks the King’s English,” laughs Jeff from California. “James is genuinely one of the most eloquent communicators I’ve ever met. He has that rare gift of being able to debate machine-learning architecture with technical purists one minute, and explain the commercial bottom line to a business owner the next.” Zac agreed: “We needed someone who had that balance. I can speak to the commercial and non-technical side, but James holds his own in front of both audiences.”

The international lineup isn’t lost on the team either. “Between Jeff in California, James in the UK, and me coming from Australia, we’ve essentially formed the tech world’s own AUKUS alliance,” jokes Zac, referencing the trilateral security pact. “You’ve got American technical horsepower, British engineering rigor, and Australian straight-shooting — sparked because two founders were sitting just desks away from each other right here in Cheltenham.”

Operating across that bridge between California and Hub8, Nimbus was formally founded in 2025. Commercial momentum followed quickly: the startup signed its first enterprise customer in November and closed its first round of capital in March 2026.

Now gearing up for its public launch, Nimbus is setting its sights squarely on workplace communications giants like Slack.

The Problem: Why Businesses Are Struggling with AI

While companies have spent the past two years racing to adopt artificial intelligence, most business leaders find themselves wrestling with a frustrating reality: the tools simply aren’t translating into real work.

Instead of lifting productivity, standalone tools have introduced clutter:

• The “Copy-Paste” Disconnect: Teams draft text in private ChatGPT tabs, then spend hours copying, pasting, and formatting outputs across disconnected spreadsheets, docs, and inboxes.
• The Slack Noise Trap: Platforms like Slack were built over a decade ago for quick human chat. Today, teams are drowning in unread message channels, buried attachments, and disjointed conversations. Tacking standalone AI bots onto Slack channels has only multiplied the noise without finishing any jobs.
• The Autonomy Fear: Leaders are understandably terrified of autonomous AI agents making unauthorised changes to live databases, updating CRMs incorrectly, or sending unchecked emails to clients.
• Runaway Costs: Generic AI setups indiscriminately send basic questions to massive, expensive reasoning models, inflating software bills without clear business return.

“Most businesses are suffering from AI fatigue,” says CEO James Campbell. “They have seen countless flashy demos that look impressive on video but fall apart in day-to-day operations. Teams are given an empty prompt box and expected to magically become prompt engineers, while their valuable institutional knowledge leaks out into disconnected chat histories.”

The Solution: The Four Pillars of Nimbus

Nimbus tackles this problem by rethinking how humans and AI interact. Designed as a Collaborative AI Operating System, Nimbus is 100% self-service — built for everyday operators rather than software developers.

The platform is structured around four foundational pillars that turn frontier AI into real, dependable work:

1. Communication

Where traditional workplace tools like Slack create ephemeral chat noise where critical decisions vanish up the screen, Nimbus grounds communication in context. Discussions, brief notes, live project data, and stakeholder feedback all live together on one clear canvas, ensuring nothing important gets lost between departments.

2. Collaboration

Nimbus introduces a true multiplayer environment where human team members and specialist AI agent teams work alongside each other in the same workspace. Rather than relying on generic chatbots, operators can hire ready-made agent teams tailored for finance, marketing, or operations to tackle complex initiatives from initial brief to signed-off deliverable.

3. Automation (Powered by “Elastic Intelligence”)

Nimbus connects directly with more than 3,000 everyday business tools, putting routine, multi-step workflows on autopilot. To keep performance lightning-fast and costs predictable, Nimbus uses Elastic Intelligence, an intelligent dynamic routing layer. Instead of burning budget by sending every query to massive models, Nimbus automatically routes routine tasks to lightweight, ultra-efficient models, dynamically engaging heavyweight frontier reasoning models only when deep, complex analysis is genuinely required.

4. Governance

Trust is the cornerstone of the platform. Nimbus operates on a read-only by default architecture. While AI agent teams can analyse data, prepare reports, and draft actions across company systems, no live system write, financial transaction, or external communication can ever occur without explicit, verified human sign-off. Every action, review, and approval is recorded in an immutable decision log, giving executives complete oversight.

Creating Tech Jobs Locally and Across the Atlantic

As Cheltenham continues its rapid ascent as the UK’s premier cyber and innovation capital — bolstered by the multi-million-pound Golden Valley development — Nimbus is already contributing to the local knowledge economy.

The business has scaled its engineering and operations, creating high-value jobs for talented UK university graduates and local developers, alongside engineering talent stationed across the American continent.

“We’re incredibly proud to be investing in UK graduate talent while maintaining that direct engineering link into the Americas,” says James Campbell. “It gives our team a 24-hour development cycle and brings fresh perspectives into how modern software should be built.”

With its public launch on the horizon, the founders are inviting organisations that want to move past superficial AI experiments to get in touch.

“This business came out of pure serendipity,” adds Zac. “A post in Cheltenham, a ping from California, and two guys sitting two rows apart in Hub8 sharing a conviction that workplace communication is broken. We’re gearing up for launch, and we want to hear from any business — locally or nationally — that is struggling to make AI work for their bottom line. Our door at Hub8 is wide open.”