I'D LIKE to write a piece about transposition, but I don't quite know how to put it across. A kind of joke. Transposer is, after all, French for "to put across". (That's enough foreign languages — Ed.)

You will need to transpose (change a song from one key to another) and I say that with confidence. "No, not me," you reply.

Okay, take Abba fans, for example. Do you really want to play "Winner Takes It All" in the sheet music's Gflat, and handle a scale of Gflat, Aflat, Bflat, Cflat? (!) Dflat, Eflat, F? Does your vocalist give up in E, G and C keys? Do brass types want to play in their C and F which is your Bflat and Eflat? Convinced?

What you're trying to do is translate a song from one key (language) into another. You go from Gflat to a nice, simple C not directly but through a code in the middle which ignores the type of chord (minor, seventh, etc) because that stays the same.

It's a system of roman numeral numbering using I, II, III, IV etc to describe the steps of a scale. Jazz and classical players favour it because they can talk about the 'shape' of a chord progression without reference to its key. For example, a pattern of II-V-I could be Dminor-G7-C or Aminor-C7-G. Saves a lot of time when a set of songs exhibits six keys, but all essentially the same progressions.

So less jazz and more Abba. We have our Gflat song and we want to take it out of that to somewhere easier.

I don't want to talk about the things we've gone through
       Gflat                                            Dflat

Though it's hurting me, now it's history
                      Aflat minor                  Dflat

I've played all my cards, and that's what you've done too
                      Gflat                   Dflat

Nothing more to say, no more ace to play
                      Aflat minor                   Dflat

The winner takes it all, the loser standing small
                      Gflat Bflat 7                   Eflat minor

Beside the victory, that's her destiny
                      Eflat 7    Aflat minor      Dflat

Back to that scale in Gflat and write those roman numerals under it (Gflat = I, Aflat = II, etc). Now translate the chords in the song to the appropriate numerals, using this 'code'. It goes I, V, II, V etc.

Now let's put it into friendly C. Take a C scale (C, D, E, F, G) and stick the numerals under that (C = II, G = V etc). Now replace the Gflat key chords in the song with the C versions — all the Is go from Gflat to C, all the IIs from Aflat minor to D minor (keep the type of chord the same) etc.

Wow, you can do the same with the notes too, so that Gflat the note becomes C the note (Dflat the movie!) and so on. It's that easy. You're instantly a social success with saxophone players, singers, clarinettist, euphonists and what have you.

But what, you say, if your song changes key. Oh, sorry, is that my bus? No, the answer is, don't panic. If the chords after the key change are a semitone away from their equivalents in the original song, retain that relationship in your transposed version. Happy transposing.