At first, a trip to Guantanamo Bay seems like a simpler prospect than paying a visit to Custodian Data Centres.

First there is the barrier into the Maidstone TV Studios site where it is located, watched by a burly security guard, followed by another set of gates to a secure car park.

After gaining access through a key-carded revolving door to a barbed wire-fenced pen, the entry to the Custodian building takes place in two stages.

After entering through two sets of electronically-controlled doors, guests must stand in an airport-security like pod, which takes each visitor’s weight to make sure they do not carry out anything extra when leaving the building.

All this is for a chance to wander the corridors of the largest data centre in the county – under supervision from two members of staff – through which £1.5 billion of revenue passes through each year.

Custodian is essentially a giant warehouse for active computers, storing servers for more than 300 clients in a series of heavily air-conditioned rooms.

It hosts the systems of FTSE 100 giants down to start-up tech entrepreneurs operating from their bedroom, all of whom want super-fast and reliable internet connectivity.

Where it has begun to make a name for itself in the data centre industry is its 100% uplink record, never having lost power for a second since it was launched in 2009.

This helped it win the custom of more established players in the sector like HostDime, a global data centre business which essentially subcontracts Custodian to house a number of its servers on the site.

The reason the Maidstone company has invited guests to tour its high-security facility is to show off its new £4 million extension, which has more than doubled the number of servers it can handle for clients from 6,000 to 16,000.

Small groups of attendees are shuffled down identical neon-lit corridors, where they peer through the small windows of prison-like doors into rooms lined with racks of flickering hard drives.

These rooms are linked up to cabling capable of sending information to London in less than one millisecond. Each is monitored around the clock by engineers and a security team, running diagnostic tests which poll the centre’s infrastructure 15,000 items every minute.

Among its customers is Mojeek, a British-built search engine being developed to rival the likes of Google and Yahoo, originally developed in the Eastbourne bedroom of its founder Marc Smith.

The search engine has mapped more than 1.6 billion pages (it would take 34 years to look at each one for a second), with its complex algorithms passing through servers all based at the centre in Maidstone TV Studios.

Its founder Marc Smith said: “Originally we chose Custodian for their location, facilities, and the fact that they were the greenest data centre in the UK, but when we decided to continue our expansion in their new data floors it was their friendly and supportive staff that sealed it for us.

“We now have over 100 servers running in their data centre. Building and maintaining a web scale search engine requires numerous parts to come together, so having a reliable and approachable team and facility like Custodian behind you, only makes that task easier.”

Custodian Data Centres was founded in 2009 by chief executive Rowland Kinch, chairman Geoff Miles and technical director Robert Williams.

It was designed to bring a new revenue stream to the TV studios, run by Mr Miles and Mr Kinch, which had access to vast amounts of power and did not need much of its huge space due to falling TV production activity.

The honour of formally declaring the data centre extension open fell to Faversham and Mid Kent MP Helen Whately, who cut a lime green ribbon in front of a couple hundred invited guests which included Kent County Council leader Paul Carter.

Her seat is among those earmarked for the chop in a redrawing of constituency boundaries before the next election.

At this rate of expansion, she might yet get another chance to hold some large scissors before her office is whipped from her.