SealSkinz Mid light Socks.  £20

Star Rating
Pro's: Warm, Breathable, Waterproof, Comfortable, Machine washable. 
Cons: None.

If you want warm feet in winter, waterproof socks are for you. Porvair seem to have bettered their previous best with the all new SealSkinz mid-light socks. At MTB Britain we've been using the popular Porelle Drys for nearly two years and found that they kept your feet warmer than ordinary socks. They did sometimes leave your feet feeling damp however, and really work more like a divers neoprene suit, keeping you warm but wet. The manufacturers Porvair, weren't content with the runaway success of the Porelle Dry product and set about developing a lighter and more flexible sock, with a truly waterproof and breathable membrane. The resulting SealSkinz Mid Light sock lives up to the designers intentions. We've had them for two weeks now and been out in some of the foulest weather. I've paddled in a freezing cold stream in them and they are a revelation. Softer and more flexible than Porelle Drys they will be on my feet throughout the Winter.

The breathability of these socks is superb, you won't suffer from sweaty, damp or cold feet in these, even on warm damp days and at around £20 they are excellent value. Thermal liners socks are also available for the coldest days, It hasn't been cold enough for a proper test of these yet though, watch this space.

Update: I've tried the liners on several long and very cold rides. Initial feeling was that they were very cosy feeling as they have a furry lining which is thicker on the inside sole. As long as you have the room for them as well as the socks without your shoes getting tight I highly recommend them. I still use neoprene outers as well on the coldest days though. This combination is unbeatable on long snow rides (our last was 6 hours)

SealSkinz Gloves. £20

Star Rating
Pros: Warm, Breathable, Flexible, waterproof, machine washable, good grip.
Cons: Not as breathable as the socks, so better suited to colder days. Wind chill can cause heat loss.

Winter gloves are a real problem. How do you keep your hands warm and dry, but still have enough flexibility to operate shifters and control the bike? Has the answer arrived in the shape of SealSkinz waterproof gloves?

Made with a different membrane from the socks they're not quite as breathable. The membrane in the gloves requires a difference in temperature between your hands and the outside air to work properly. In practice this means they will feel clammy on warm days. On wet and windy days and when the temperature drops below 10 degrees C however they perform superbly.

They are extremely flexible in use and have good grip due to the palms and fingers being studded with hundreds of tiny rubber dots. I'll probably choose to keep them in a pocket (they are thin and light) until the weather deteriorates. As with the socks, thermal liners are available for the coldest days, we'll report back on these when the we've tested them below freezing. - see below.

Update 1: Got another chance to try these out in the Peaks the other day, found them excellent for ripping off a wet and muddy tyre to change a tube. The grip of these gloves is truly impressive.

Update 2: I was wearing these in a blizzard which turned to sleet on an exposed hilltop. I found that the combination of water on the gloves and the wind chill was causing my hands to freeze even though the gloves are waterproof. Following this experience I bought a pair of Pearl Izumi Aquanauts. Report on these gloves soon. Initial findings are that they're way too warm for most days.

The socks and gloves both work with a 100% waterproof layer (membrane) which is concertina'd to allow it to stretch.

The material is able to pass water from molecule to molecule. This process is driven by heat. When the temperature on the inside is greater than outside, water is driven out. On a hot day this won't work, as there is not enough difference in temperature between your body and the outside air.

For more technical stuff see SealSkinz.com