This was after some research most likely a Great crested newt.
Great crested newt, Triturus cristatus.
A European Protected Species, the great crested newt is dark brown with a row of white spots on its head and body. The male is smaller than the female and will develop the large and distinctive waved crest along its back during the breeding season.
Other newts common in the UK much more varied in colour:
Palmate newt, Lissotriton helveticus.
This is the smallest native newt in the UK. Males are an olive-brown colour, females can be yellow to olive-brown. Males also develop a low, smooth dorsal crest during the breeding season. Palmate newts have an unspotted pinkish throat and yellow bellies with small black spots.
Smooth newt, Lissotriton vulgaris.
This is the most widespread newt in the UK. It is smaller than the great crested newt, but very similar to the palmate newt. However, the males have a much more developed wavy dorsal crest than the palmate newt during the mating season. Both sexes also have dark spots on their white throats, which palmate newts do not. The female lays individual eggs, wrapping each one in the leaf of an aquatic plant.
From the colourings it was not one of the few UK lizards that we have, as all are much more colourful or lighter browns (see Lizards: identification)
Source: Amphibians - Woodland Trust