The new unit is a rugged and waterproof handheld in the same vein as the TX3 but packs more power and features into the bargain.

As with the TX3, the TX4 can also be used as a smartphone with the addition of a SIM card, but also boasts a 4-inch high-resolution touch screen, an 8-megapixel camera and WiFi, BlueTooth and 3G connectivity.

There are several options to purchase one, starting at £349.

Buy it with Ordnance Survey’s Landranger mapping for Great Britain, and you’ll pay a mere £379, while the top package – a Platinum Edition GPS pre-loaded with 1:10,000 Street View, 1:25,000 Explorer and 1:50,000 Landranger mapping – costs £499.

Trade-in an old unit direct with Memory Map and it will give you £50 off these prices.
We tested the TX3 in our February issue, while out and about walking in the Peak District.