I've done piano grade 5, but haven't done grades in along time. I'd say its of a high 7/8 standard though.
I know im really breif about everything, but just wanted to get some famous tangoes to see if it came up

And nope jane, it isnt libertango

*sigh* its so frustrating, it's the kind of tango you will all recognise

I hear it all the time!
oh forgot to mention, I asked my friend at school who knew it, and worked it out on the piano to be:
E ^E C A.. E F E Eb E
^ standing for up an octave. Haha, that will probably make no sense, but the last 5 notes might click.