Mole
The picture is a cheat, taken from the internet’s public domain. We haven’t seen a mole in the park, only lots of recent molehills in The Arboretum.
Moles (Talpa europaea) live their whole lives underground, rarely, if ever appearing on its surface. They move through the soil in a way that has been compared to swimming, and their whole bodies have become adapted to this three dimensional, subterranean living.
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[1] A molehill in The Arboretum; [2] the mole’s front paw adapted for digging.
They are streamlined in the same way that a swimming seal is streamlined: a pointed face, invisibly small ears, rounded head and tapering body, and a smooth coat of dense, dark grey, water-repellent fur. Because they do not need to lift their weight up (it is supported by the soil), moles’ front limbs stick out to the side like a seal’s flippers, and are used to push the soil backwards, the way a breast-stroke swimmer pushes the water back. The front paws are huge and spade-like, with long, strong nails, adapted for digging.
Their life spent in the dark, moles have very poor eyesight but to compensate they have evolved movement-sensitive cells right on the end of their nose to help them find their unseen prey. Moles are classed as insectivores: they eat worms and the underground larvae of insects. They need to eat around half their body weight each day in order to survive; the presence of moles in the park is a tribute to our rich biodiversity.
The Arboretum as the leaves begin to change.
Southwick Country Park Nature Reserve 
Google images have pictures where somebody found a dead mole and buried it up to its armpits then took pictures that look like its coming out of a molehill. At least you found one that looks like its alive. Well done.
I saw those! The internet is full of tricks and lies.
There are lots of molehills in the field as you enter the park from School Lane!
Your comment was made anonymously so I have renamed you as A Park User because it is our policy to delete anonymous comments. There is no need to leave an email address but we would like you to leave a name; any will do. Thanks for the comment; it’s nice to know that there are moles in places other than The Arboretum.