Station Despatch which is entirely outdoors, including night shifts, is one of the coldest jobs of the lot. As the job does not really include much moving around (just walking to your next train), you get really cold.
Fuelling and tanking Units can be cold in Winter on nights but its constant lifting of pipes so you get warmed up fast. Again, outdoors 100% of the time, and always at night. The worst part is keeping your hands warm as your touching cold steel while wet if you get covered in toilet water/CET which you often do. Then you have to wear cloth gloves but they get wet and fuel soaks through them to your skin so you have to keep changing them and wear a set of plastic disposable gloves underneath for protection. Other than getting cold hands its not too bad as you dont really feel that cold unless its about minus 7 due to all the lifting and humping pipes around and you can wear a white suit which keeps you warmer still if needed, but unless it is very cold, you can overheat with it on when the hard work really gets going.