Apologies if this has already been covered, only had time to skim through the topic. In the UK base speed is just speed (i.e. amphetamine sulphate) but not cut as much as regular speed. It generally comes as a putty/paste as the OP mentioned (this is how dealers buy it before cutting it with powders to make a powder), but the term is not well defined and can mean any speed that isn't cut to shit (though even the best stuff will still be very impure). In terms of effects there really is no difference between base and normal speed, except perhaps for those that might be caused by any of the cuts (speed can be cut with baking soda which would certainly affect the high).
It is definitely not freebase amphetamine.
It is definitely not freebase amphetamine.
