A neighbour’s cat watches intently through the hawthorn hedge from its vantage point on next door’s concrete coal bunker.
It pounces and chases a brown rat, coming close to catching it. The rat looks healthy enough but it has been behaving strangely, roaming about in the afternoon sunshine, showing little concern for danger. For a while it stopped and was nibbling at the edge of the frosty, still mainly snow-covered lawn. 
Perhaps it has eaten poison bait put out by one of our neighbours and it’s now feeling thirsty, which seems to be one of the symptoms of rat poison. Ponds are currently deep frozen so perhaps it was quenching its thirst with ice crystals.
Happy New Year Richard. The behaviour of the rat matches the symptoms of Toxoplasmosis, see the Wikipedia article http://en.m.wikipedia.org/wiki/Toxoplasmosis#Rodent_behavior for details. Best regards, Roman
That sounds very like the behaviour of the rat, which we haven’t seen since (perhaps the cat caught up with it). The neighbourhood cats on their way to and from the happy hunting ground of the meadow do sometimes use our raised veg beds as giant-sized litter trays and the rats occasionally burrow in them too, so it would be prudent to assume that Toxoplasmosis protozoan might be present from time to time. I must keep wearing gardening gloves!