Essential winter clothing?

Hot/warm: mitts (Spesh BG but any really), cycling shorts, short sleeve jersey, socks, Spesh MTB SPD shoes, casquette

Cooler (where I am as of this morning):

• Add a windstopper gilet
  
• Next add roubaix backed arm warmers (still wearing short sleeve jersey)
  
• Swap mitts for full finger gloves (Spesh BG are the ones I have)
  
• Next add roubaix knee warmers
  
  

Cold:

• Buff to cover mouth/ears (especially as first part of my commute is downhill)
  
• Cotton inner gloves over the full finger gloves (not waterproof but opting for warm+wet option)
  
• Skins leggings (still with Knee warmers on top)
  
  

Even colder:

• Long sleeve jersey instead of s/s jersey + arm warmers
  
• Swap windstopper gilet for Gore Alp-X jacket (had it for 10 years, thin but lovely)
  
• Swap to Altura Waterproof gloves if really rainy
  
• Woolly hat or Gore thermal cap instead of casquette
  
• Short sleeve skins top under jersey
  
• Swap Skins leggings for full length roubaix backed leg warmers
  
• Second pair of socks (never really suffered from cold feet to bother with anything else)
  
  

Freezing:

• Extra base layer (or long sleeve Skins) under jersey
  
• Skins leggings added under the leg warmers
  
• Softshell jacket (cheap eVent thing from Evans)
  
• Schwalbe Marathon Winter spiked tyres
  
  

I've never bothered with overshoes, even on really long rainy rides (30 hours+ of Welsh "sunshine" on the Bryan Chapman 600). I opt for the "warm and wet" strategy rather than trying to avoid getting various bits wet.