Loss of power in freezing conditions

Hi all, new to Landys and LandyZone and have tried to find a relevant thread but can't. I have an M reg 300tdi Defender and live in the Highlands. I bought the Landy in the summer and had no problems at all with starting (except I bought a new battery 1 month ago for the winter). I tried to start the car this afternoon and it took 4 attempts to start, it appeared to be a lack of fuel as it fired once and stopped on each occasion. Once started the engine would not give any power and I could not go faster than about 5-7 MPH and I could only travel in 1st or 2nd gear due to the power loss, again it seemed like a fuel shortage. I left the Landy on the drive with the engine running (as usual no smoke etc) and after about 20 mins the car was back to its great running. The outside Temp is about -15 but I am sure it has been colder. The fuel filter etc was renewed by a specialist Landy garage just before I bought it. Please can anyone give suggestions on what this may be and how to prevent it happening again, thanks.

Mine is hard to start and won't rev in the cold on first startup. I just put it down to the cold temp making the lube and fuel oil thicken up and everything slow down. After a bit of cranking, oil pressure builds and the dash light goes out. When I stop cranking the oil pressure light takes AGES to come back on so I'm thinking the oil is like toffee or maybe treacle. It can't be doing it any good to try to rev it when not lubricated like this.

Once warmed up a little she kicks **** as usual.

I would check the heater/glow plugs.
These come on to start but do not go straight off once the motor is running but remain on to warm the air up as it enters, I believe.
Once everything warmed up the air temp going in would have less effect.
Or.. the filter &/or the water trap(sedimenter) at the back has iced up.
I am a new boy too but learning fast(loads of practice).

Thanks Guy's, I will check the sedimenter but I dont think there is a problem with the heater plugs as there is not usually a problem with startin or running.

Could be diesel is starting to wax-diesel in the UK is guaranteed only to -15c.The way round this is to add some unleaded-up to 30% max is recommended by manufacturers in Scandinavia._In your case i would add 5% to 10%,it will not do any harm,but it needs mixing so have a drive somewhere bumpy to slosh the tank around-I run homemade bio and are already adding around 20% petrol.
If the diesel does wax it will start and then die on you-if this should happen,boil a kettle of water and pour the boiling water gently over the fuel filter,injection pump,the injector lines(as much of the diesel pipework you can get to),wait 20 secs or so for the heat to sink in,and then try starting again-always worked for me ,on any diesel I have owned.

I was going to say it could be waxing up . As its bee stood now , take off your fuel filter and pour the contence into a glass , if its cloudy then its its starting to wax up . But as above will work .

Where about in the highlands are you? I have had this problem with my disco lately as well. I live nr aberlour.
I removed 2"of ice from the sediment bowl and then it wouldnt seal so i removed it altogeather, Though I had it fixed then last week the same thing happened. I drained water from filter and it has been fine since.