A helpful book on this topic is "Temperament: the Idea that Solved Music's Greatest Riddle" by Stuart Isacoff (published by Alfred A Knopf, New York 2001). It deals with the technical issues thoroughly, but in a relatively jargon-free manner. It also sets the search for better tuning systems in historical context, though readers who just want the musical information can skip these passages and still get the fundamental message.

Howard Goodall's TV programme is also very useful – and entertaining – though some of the technical points flew past so quickly that I needed to replay them a few times to follow him. (The DVD is advertised as available from Amazon.)

However, I've found nothing in print or online which applies this technical information to the tuning problems which afflict the average folk guitarist. Even when your guitar is properly set up and accurately tuned, when you play the standard first-position C chord, the top E string sounds a bit sharp. So, you twist the tuning peg till it sounds better and play. So far, so good.

But later, when you play a first-position E chord, the top E string sounds flat.   You twist the peg again to pull it up – and then you notice that the G# on the 3rd string sounds a bit sharp, so you adjust that, and play away happily. All is well while you keep playing in the key of E, but when the next song in C comes along, your 3rd string sounds flat, while your 1st string sound sharp. And so it goes on – and on – and on.

This problem haunted me for decades, until I eventually learned that the major third interval (C – E in the key of C, E – G# in the key of E) is 17% sharp of the "natural" major 3rd. Even those of us with fairly insensitive or untrained ears can tell the difference – but when we try to put it right, we often make things worse. So, what's the solution? Basically, there isn't one - but there are techniques that can alleviate the problem somewhat.

1) Make sure your guitar is properly set up, put good strings on it, change them regularly, and tune them carefully with a good electronic tuner.   After that, don't keep tweaking to try and improve things further, as this is more likely to hinder than help.

2) When you strum chords, try to avoid sounding the 3rd note in the chord (E in C, G# in E, etc) on the first or second strings, where it seems to be more noticeable. For example, try playing the 1st position C chord holding down a G note (1st string, 3rd fret) with your little finger, instead of having an open-string E.   (There are similar work-arounds for other common chords.)

3) Try playing in open tunings like DADGAD and using chords without the third interval in them – when you have to fret a 3rd as a passing note, it's less noticeable against the jangling background of root/5th drones. Or play in open tunings with a slide and avoid the fretting problem altogether.

4) When playing jazz, blues and rock music (and also some kinds of East European and Asian music) hit the note one fret below the one you want, and bend it up until it sounds right. (If it was good enough for Broonzy, Django and Hendrix …)

I could go on, but this post is too long already.

Wassail!