Winter clothing is all about keeping you comfortable. Not to hot or too cold. So, you need to have a flexible clothing system. That is why it is best to dress in thin layers. Each layer does a slightly different job to keep you comfortable.
1st Layer: This will usually be a snug baselayer. They come in a few different weights or levels of warmth. Which level is right for you will depend on whether you are a warm or cold person. Unless you run really hot or are only going out for 20 minutes at a time having this layer snug is essential. Otherwise you will get damp patches that will cool and make you feel uncomfortable later in your run.
2nd Layer: For running in the UK for most runners a two layer system is all you need. The second layer would be a mid-layer on a cold dry day or a jacket on a wet or particularly windy day.
Mid-Layers: These are designed to pull the moisture from the baselayer spread it out and dry. A thin layer if often enough but, as with the baselayer this depends on how warm or cold a person you are and how warm you like to feel when running. The fit of this will be baggier than the baselayer.
Jacket: It is important to realise that the more waterproof the jacket the less breathable. So, although we sell some Waterproof jackets we would not recommend these for day to day training around the streets as you will get too warm. If you are particularly warm then a Gillet (jacket with no arms) would be better as it will keep the worst of your chest but, allow you to breath and good baselayers will still keep you warm when you are wet.
The Legs: On the legs it is best to wear tights as these keep you warmer by being snug fitting. Generally there is too weights. A smooth inside and a brushed inside. The brushed ones are warmer. Tights tend to go up in price dependent on the number of panels. The more panels in the tights the more work to make them and the higher the cost but, the tight will fit better. In a shop you can tell the better fitting tights as they tend not to look good on hangers. If you don't like the idea of tight fitting leg wear then RonHill Tracksters are a good alternative. These are lighter and less baggy than tracksuit bottoms and made of breathable material that doesn't absorb the rain. If you are super warm you could use 3/4 length tights which are cooler than tights.
Underwear: There is little point buying a nice well fitting breathable pair of tights and then wearing your cotton pants under them. The moisture will be absorbed into the cotton and you will get a cold bum and maybe some chaffing. So, buy breathable briefs. The same is true for cotton bra's. A running bra doesn't just give good support it is also breathable and drys quick so it will keep you warmer and chafe less.
Hats and Gloves: Ideally you want a hat that feels snug when you first walk out the door on a cold winters night but, that doesn't get so hot you want to take it off after 10 minutes. The same is true for gloves and how hot or cold you are as a person will have a bearing on the item you choose.