Start with the compass, not the furniture

Before you move a single cable, work out which way your window faces. On an island, that single fact shapes everything: how warm the room gets, how badly your screen glares, and whether you can work comfortably at two in the afternoon in January without reaching for a lamp.

A rough guide to what each aspect gives you:

• South-facing: the strongest, steadiest light of the day, but also the biggest glare risk on a monitor. Best worked side-on.
• East-facing: glorious morning light that fades by early afternoon. Ideal if you start early and want the room bright when you're sharpest.
• West-facing: afternoon and evening sun, wonderful for late workers, though low summer sun can land directly on your screen.
• North-facing: the quietest, most consistent light all day. Often the kindest aspect for long stretches at a screen.

If you have a choice of rooms, this is the one decision that will do more for your comfort than any lamp you could buy.

Position the desk so the window works with you

The commonest mistake is facing the window head-on. It feels logical — you're looking at the view — but bright glass behind your monitor forces your eyes to constantly adjust, and you'll end up squinting by mid-morning.

The other extreme is sitting with your back to the window, which throws your own shadow across the keyboard and turns the screen into a mirror.

The best compromise is to sit at right angles to the glass, so the window is at your side. Your monitor then sits perpendicular to the window wall, and daylight falls across your desk rather than into your eyes. If you're right-handed and the window is on your left, even better — your writing hand won't cast a shadow over your work.

Leave a gap of roughly 60 to 90 centimetres between desk and window. Too close and the contrast between bright glass and dim interior becomes uncomfortable; too far and the light has faded before it reaches you. If you must face the window, keep the top of your monitor below the brightest band of sky, and tilt the screen very slightly downwards.

Use mirrors to move light deeper into the room

Island houses often have deep window recesses and thick stone walls, which means daylight stops about a metre inside the room. Mirrors are the cheapest way to push it further.

• Hang a large mirror on the wall opposite the window. It effectively doubles the amount of light reaching your working wall.
• Tilt it a fraction downwards so it bounces light up onto a pale ceiling, which then spreads it softly around the room.
• Add a smaller mirror on a side wall to catch light onto your keyboard or the page you're reading, angled so it never crosses the screen.
• Avoid anything reflective directly behind your monitor, including glossy framed pictures. You'll see nothing but reflections.

Frameless mirrors look calmer and reflect more. Beyond glass, pale surfaces do quiet work: a white desk mat, a light-coloured noticeboard, a glass-topped table. Dark, heavy furniture near the window soaks up exactly the light you're trying to keep.

Choose curtains and blinds that don't eat your daylight

The biggest daylight thief in a home office is a curtain stack. Heavy drapes bunched at the sides of a window can swallow a fifth of the glass, even when they're "open".

• Fit the pole or track 15 to 20 centimetres beyond the window reveal on each side, and around 10 centimetres above the top. Curtains then stack over the wall, not the glass.
• Choose voile, half-curtains or a light linen for daytime privacy. Sheer fabric filters without blocking.
• Prefer Roman blinds to rollers, and mount them outside the recess so a raised blind clears the glass entirely.
• Shutters with wide slats are excellent: tilt them to bounce light up onto the ceiling, and keep the lower half open on bright days.
• Line curtains in a pale fabric rather than a dark one. Thermal lining is worth having for winter evenings, but draw it at dusk, not at three o'clock.

Whatever you choose, keep the fabric pale and the mechanism simple. Anything that needs untying, unhooking or wrestling loose will stay shut longer than you intend.

Work with island light through the seasons

Island daylight is not the same as mainland daylight. In the Northern Isles, the summer simmer dim means near-constant light in June — useful for an early start, but you may want a blackout blind simply to protect your sleep. In the Outer Hebrides and Shetland, midwinter can offer barely three or four hours of genuinely usable light on a grey day, so plan accordingly. Put demanding screen work in the middle of the day and save email, admin and phone calls for the dim edges.

Sea glare deserves its own plan. Low sun bouncing off water arrives flat and hard, and a desk that's fine in April can be unusable in October. Sometimes the answer is simply turning the desk to face a different wall for the winter months.

Salt haze and sea fog also film your windows faster than you'd expect. A monthly wipe with warm water and a splash of vinegar restores a surprising amount of light, and cleaning the outside of the glass matters more than the inside.

Small changes that make a room brighter

• Keep window sills clear. Plants, ornaments and paper stacks all cast shadows onto your desk.
• Paint the window reveal, ceiling and walls in matt white or pale tones. Dark colours absorb the daylight you're trying to harvest.
• Trim hedges, move the bin store, and check that new fencing or a shed isn't shading your window.
• Pull bulky furniture away from the window wall so it doesn't loom over your working space.
• Prop a sheet of white card on the sill as a simple reflector — it lifts light onto the desk on dull days.
• Test your setup at the times you actually work. Ten minutes watching where the sun lands will tell you more than any rule of thumb.

Get these basics right and you'll find the lamps stay off until teatime, even in February.