Originally Posted by: English Enigma erm , cant remember the make, but it looked like the boss range. [/QUOTE]
Then most probably it's what they call a vibrato pedal , it changes the volume intensity with time to give a vibrato like feel , or what the vocabulary freaks like to call "tremolo" ;) .... But practically , you'll find almost every amp and effects manufacturer call it vibrato.

[QUOTE=English Enigma] So the whammy bar or whatever its known as, that screws into your guitar is to do with vibrato not tremolo, now i understand.

Well , people call it whamy , tremolo , vibrato bar (actually , the first two are the most popular ) ... It doesn't matter what it's called , but whenever you hear/read one of these words folowed by "bar" , you'll know what it is .