Ok maybe i was setting the bar a bit high as some of the posters over there are using things like cardboard and lint, i was thinking it had to be "bushcraft" style man made!
Since some of you have already suggested it i may have a go at making char cloth if anyone can tell me how to do it?
Get an empty syrup tin (enjoy the contents - don't waste them!) a tea towel (preferably new as soap residues from laundering them is a fire retardant - Tesco 100% cotton terry loop are my favourite but then I just like burning anything to do with Tesco...) and a nail.
Get a good hot fire going.
Punch a hole in the lid of the tin with the nail and keep the nail handy.
Stuff the towel into the tin - 1 towel fits just great into 1 tin - do not faff with cutting it up as this is a messy waste of time.
Put lid on tin.
Put tin into the fire.
Columns of smoke should pour from the hole in the top and may well later become columns of super heated flame in the manner of a jet engine - enjoy the show!
When the smoke and or flame dies away to nothing or very close to it remove the tin from the fire - use tongs - it is hot...
Push the nail into the lid to prevent any oxygen getting in or you will just end up with ash as the char cloth uses the oxygen to burn... wadda you mean you can't find the nail?
Quick turn the tin upside down in the mud and press it down to seal it!
Wait until the tin is ice cold to the touch (it takes a good while - be patient or you will get a view of your towel glowing away to ash as you let in all that oxygen) then open up your tin and remove the shrunken black remains of the towel.
You should be able to unfold he black carbon that was once the pride of Tesco if you are careful and have the muckiest towel on earth in your hands. If it has brown or white bits on it - you were impatient and took it out of he fire too soon (rushing jobs gets you nowhere - have you learned nothing from your teachers? ) these "brown ends can be added to your next tinfull to finish off.
The black bits should tear easily to the size you want to use - if they are crisp and crumbly they are over cooked (you got bored and looked away, didn't you, and you missed when the smoke stopped) if the tin is full of foul smelling black lava-like deposits you did not read the label on the towel and used Polycotton - use 100% cotton you pilchard!.
The nice black carbon of a well charred towel should take the smallest dullest spark and turn it into a huge glowing ember.
I hope that helps