Thirty years ago this weekend, when Apple began life as a business, it was Steve Jobs who chose a name for the brand-new company. He named it Apple, the same name used by The Beatles’ record company.

Steve probably didn’t think that would ever be a problem. After all, a British music business and a (then very new, very small) Californian computer company - no-one would have expected the two to have any conflict.

But Apple Computer did better than anyone expected, and was soon a global brand. The executives in charge of Apple Corps started to take notice.

And that’s why the two companies came to a trademark agreement in 1991. Apple Corps said Apple Computer could continue using the Apple name, on one condition - that it never go into the music business.

Ooops.

That’s what the court case, which opened today at the Royal Courts of Justice in London, is all about.

When it comes down to detail, Apple Corps is not saying that Apple Computer should stop selling music online - it has no problem with the iTunes Music Store. The problem boils down to the use of the Apple logo, displayed at various stages of the music downloading and buying process.

Geoffrey Vos QC, who opened proceedings today on behalf of Apple Corp, said that in selling music online and using its logo this way, Apple Computer was doing “exactly what they cannot do” under the terms of the 1991 agreement.

He said: “Apple Computer can go into the recorded music business in any way they want. What they cannot do is use Apple marks to do it.”

Apple Computer’s response so far (remember, the case has only just opened) is that iTunes is a “software delivery system”, merely a “conduit” through which music happens to be sold.

Apple Corps seeks to stop Apple Computer using the logo for online music, and damages. If it wins, Apple Computer may have to pay a large payment - and employ someone to design a new logo for the iTMS.

This is by no means the first time the two Apples have resorted to legal action to settle their differences. The case continues tomorrow, when Apple Computer’s lawyers will outline their case.