Where it started: a free personal attack alarm for everyone
The Sentry launched in the UK in 2021 with a simple, powerful idea: every smartphone should be capable of raising a credible personal safety alarm at a moment’s notice — for free.
The original app let anyone transform their phone into a personal attack alarm. One touch triggered an audible siren and automatically alerted nominated contacts with location data. It was designed for anyone who felt unsafe: lone commuters, university students walking home at night, shift workers leaving late.
The UK launch was announced via a Presswire press release in June 2021, positioning The Sentry as a free, accessible alternative to expensive personal safety hardware. The core philosophy was that personal safety technology should not require a subscription or a device purchase.
The problem with generic safety apps
The consumer personal safety market quickly revealed a structural problem. Generic apps serve everyone, which means they solve no single use case perfectly.
Emergency contacts vary — a student’s emergency contact is different from a lone worker’s line manager. Escalation workflows are different. Evidence requirements are different. Insurance and legal considerations are entirely different.
For professional environments — particularly estate agents conducting solo property viewings — the generic app model created compliance gaps that could not be papered over:
- No encrypted audit trail of session activity
- No employer dashboard for real-time monitoring
- No whistleblowing-compliant incident reporting channel
- No compliance documentation tied to specific legislative standards
The platform that worked as a consumer alarm was not the platform that could satisfy the Worker Protection Act 2023 or the HSE INDG73 guidance.
MWC Barcelona: scaling the mobile safety vision
Before pivoting fully to the property sector, The Sentry exhibited at 4YFN (4 Years From Now) at MWC25 Barcelona — the startup summit that runs alongside Mobile World Congress, Europe’s largest mobile technology conference. The MWC Barcelona exhibitor listing references the platform’s focus on mobile phone safety and thesentry.co.uk as the developer contact.
4YFN is one of the largest startup gatherings in Europe, focused specifically on mobile-first technology businesses. Being selected to exhibit as a UK company at MWC 2025 placed The Sentry alongside some of the most ambitious mobile technology startups globally — and confirmed that the underlying technology had commercial depth beyond the consumer market.
The MWC experience crystallised what would become the defining insight behind the property sector pivot: the most underserved market for mobile safety technology was not consumers, who had dozens of app options — it was professional workers in specific high-risk verticals who had no purpose-built solution at all.
The pivot: purpose-built for UK property
The property sector presented a specific, compounding problem. UK estate agents and lettings negotiators routinely conduct solo viewings in unoccupied properties with clients they have never met. The combination of isolation, physical vulnerability, and reputational risk — particularly for female negotiators — created exactly the environment where a purpose-built professional safety platform was urgently needed.
The pivot was not a departure from the original mission. It was a sharpening of it. Instead of building a tool for everyone, The Sentry would build the definitive safety platform for one sector — and build it correctly.
This meant:
Sector-specific workflows — check-in timers calibrated for property viewing durations, not generic safety sessions.
Employer-facing compliance tools — an admin dashboard that gave agencies real-time visibility of their field team, not just contacts receiving a personal alarm.
Legislative alignment — compliance documentation mapped directly to the Worker Protection Act 2023, the EHRC 8-step guidance, and the Employment Rights Act 2025 whistleblowing protections.
One-hour deployment — the property sector is dominated by SME agencies without dedicated IT teams. The platform had to be operational in under an hour with zero hardware.
Why the property sector specifically
The UK residential property sector employs over 500,000 people across estate agencies, lettings businesses, and property management firms. It is the largest industry sector with a persistent lone worker exposure outside healthcare — and arguably the least protected.
Healthcare lone workers have NHS frameworks, union guidance, and mandated risk assessment processes. Property workers have, in most agencies, a WhatsApp group and a culture of informal check-ins that carries no legal weight under the Worker Protection Act 2023.
The October 2024 commencement of the Act, combined with the Employment Rights Act 2025 extending strict third-party harassment liability, created a compliance environment that could no longer be satisfied by informal process. Agencies needed a documented, operational safety system — not a consumer alarm app, and not an enterprise platform priced for a 500-person company.
The Sentry filled that gap at £39.50 per user per year.
What the platform provides today
The current platform bears the DNA of the original 2021 launch — fast, mobile-first, no hardware — but it has been rebuilt around professional compliance requirements:
- One-touch panic alarm with automatic video capture — creates tamper-proof incident evidence, not just an audible alert
- Real-time GPS monitoring via admin dashboard — gives employers verifiable oversight of field staff during solo viewings
- Private, EHRC-compliant incident reporting channel — satisfies Step 4 of the EHRC 8-step guidance and ERA 2025 whistleblowing protections
- Compliance documentation pack — policy templates, risk assessment frameworks, and legislative mapping included at no additional cost
- Full encrypted audit trail — admissible as legal evidence in employment tribunal proceedings
The Sentry is listed on both the Apple App Store and Google Play with full feature descriptions, and thesentry.co.uk remains the developer contact across both stores — just as it was at launch in 2021.
A self-funded, independent business — by design
The Sentry has remained self-funded throughout. That independence is not incidental — it is a deliberate commercial and ethical choice.
Venture-backed safety platforms face pressure to expand pricing, add hardware requirements, and extend contract lock-ins to satisfy investor return timelines. The Sentry has no such pressure. The pricing model at launch — accessible, transparent, no lock-in — remains the model today.
From a consumer personal alarm app in 2021, to an exhibitor at MWC Barcelona, to the UK’s dedicated lone worker safety platform for the property sector: The Sentry’s evolution has been defined by one consistent principle — safety technology should be accessible to everyone who needs it, not just those who can afford enterprise pricing.
Stuart Evans is founder of The Sentry. The Sentry is based in the UK and has been self-funded since founding in 2019.