"He wrote it for me, but the record company had the power to prevent any other record coming out and they said, ‘This is a number one smash: Beck doesn’t get this’”: The story of the Stevie Wonder and Jeff Beck connection

Jeff Beck and Stevie Wonder attends 2011 MusiCares Person of the Year Tribute to Barbra Streisand at Los Angeles Convention Center on February 11, 2011 in Los Angeles, California.

There's no ultimate test of what makes a great guitar instrumental. But fine melody, emotive performance and technical prowess are a pretty good start. Top-notch production won’t hurt either and success in the charts does at least tell you that a lot of people like it.

One particular barometer, however, informs us that other great musicians also think it’s cool:  when you find guitar and amp demonstrators performing it at trade fairs. These guys are at the top of their game, understand composition, recognise ability and know all about tone.