Winter in the Outer Hebrides seems to conjure two words in peoples minds – both of which seem to make us slightly odd to have come here in winter in most southerners minds. The first is dark, because surely this far north it will get light so much later and dark so much earlier. Oddly, it gets dark later than it does in say London, but I have to admit that it gets light about an hour later. This is because sunrise advances from SE to NW at this time of year so it is much later, but sunset comes rather more from a rather less oblique angle. And it actually starts to get light, technically the twilight hours, before and after sunrise/sunset much earlier/later than you would expect, so in the morning and afternoon you can get the most amazing sunrises and sunsets. The reason for all of this is that the sun is moving at a much more oblique angle to the horizon as it crawls over the horizon and heads for the heights at midday. I am sure there is a complicated way of working out how high it actually gets, but all I know is that in some complicated way our latitude 57.5 degrees north decimal and the tilt of the earth to the sun means that at this time of year it struggles up to get higher than about twenty degrees above the horizon, which gives very oblique and thus very weak sunshine.

Logically, weak sunshine can mean only one thing – cold. That would be true if we didn’t have the largest heat store on the planet running past the front door and in this case it really is nearly our front door. The North Atlantic Drift is a huge mass of water driven by the trade winds on the equator. It is in fact hardly imaginable how much water it contains – 150 million cubic metres are moved north every second. The movement north also means that water warmed in the Equator and the Caribbean comes north to flow past the Outer Hebrides. The result is that whilst London is currently 8 degrees celcius, we are currently in a balmy 10 degrees and all talk of freezing temperatures is only relevant to the south and east. But all this does depend on the wind direction, so last week when a huge northerly gale blew in from the Arctic all bets were off and we were treated to some magnificent hail storms that gave the Harris Hills impressive white tops. So we hope the wind continues to blow over the radiator to the west.

The temperate weather goes some way to explain the extraordinary richness of archaeological remains in the area, although the climate was much warmer up until about 5000 years ago (and the sea level about 30 metres lower meaning there is a whole lot of archaeology under the sea). What is left is amazing, but the most amazing is the Callanish Stones in Lewis. It is a huge set of stones, made from the local stone whose formation predates its use by man by over 3000 million years and thus makes it some of the oldest rock on the planet. As with many such stone circles, it is aligned with both the summer and winter solstices, some moon rises, as well as being aligned to a time when the sun runs down the outline of a reclining body of a woman traced by the hills of Harris. Were the ancients hoping to forecast the arrival of snow on the hills, or plant their seeds in the spring, or many of a huge variety of other events that are seasonal. We will never know, but I think they were hoping to predict the arrival of the greatest run of migratory fish in the islands. Nowadays these are important to two of the best salmon fisheries on the island, which are literally next door to each other. Both are fed by a run of salmon that has to negotiate the same narrows at the foot of the stones.

See, everything comes back to fishing.

After we first decided to spend six months in North Uist I started preparing a list of things that I really wanted to do whilst we were up here. A few covered the fishing and mainly centred around catching a big sea trout. I managed a 5lb beauty from Ard Heisker sea pool, only to be topped by my brother catching one of 6 1/2 lbs, a proper beauty that had been in Vallay Loch for about a week and was only just losing the losing the silver colour, but had the most wonderful lilac colour. Suffice to say that both fish were returned – no fish that has attained that kind of weight should be removed from the breeding gene pool.

What I hadn’t reckoned on is that one of the items on the list, one nearly at the top, was to appear rather unexpectedly during Poirot last week. Is it just me or is there always a moment when you realise that A. Christie has rather given the game away and your mind wanders. In this case my mind had wandered as far as looking, more in hope than expectation, at Aurorawatch UK – the must see web site for anyone remotely interested in seeing the Northern Lights. To see the Aurora Borealis, as they are more technically described you need a very dark sky to the north of you and a sun spot derived magnetic storm. The further south you are, the bigger the storm, but with the very biggest storms you can see the Northern Lights as far south as the Scilly Isles (but you are usually thwarted by the glow of urbanity). We certainly have dark skies up here – from the lights of the airport far to the south around a sweep of 180 degrees we cant see one light, except for the distant flash of the Monarch Isles lighthouse.so all we needed was a magnetic storm. We had already missed a fantastic display last month, when it was described as psychedelic. I simply thought it was the moon behind the clouds and gone to bed, which was a bit stupid as it was a New Moon that night.

We have the dark skies, so all we needed was a magnetic storm. And the only way of knowing if there is a storm is to look at Aurorawatch and see what their detector is saying. Most of the time it is rather disappointingly green, but this time I idly called up the web page on my ipad to discover that it was Amber. Possible aurora. Abandoning Poirot (body buried under folly, husband killer) I went outside and was faced with the most amazing light display I have ever seen. Against the inky blackness of the northern sky was an extraordinary veil of green, like diaphanous curtains hanging from the sky being blown gently in a cosmic breeze as they wafted backwards and forwards across the sky. As this was my first experience, i can’t say if this was a great display, but it really was pretty sensational. The light is caused by the magnetic storm exciting the oxygen and nitrogen in the atmosphere so they actually glow – hence the fabulous green glow. Occasionally the storm is severe enough to make them glow red, but only when Aurorawatch is reporting red status – severe storm. So in aurora world amber means possible green and red means possible red. Wonder if Poirot would approve.