Cadbury has fought off Nestle over exclusive rights for the distinctive purple colour it has used on chocolate wrappers for more than 100 years. The Cadbury brothers are thought to have picked the colour as a tribute to Queen Victoria.
The group, which has been in a legal battle with its Swiss rival for three years, was granted a trademark for the tint - pantone 2865c - to be used on goods such as Dairy Milk, in 2008. Nestle challenged the ruling, saying the colour was not distinctive enough.
The UK Intellectual Property Office this week ruled in Cadbury's favour. One legal expert said that while it was an interim judgment, the decision was unlikely to be changed in the final report.
A spokesman for Cadbury said the group was pleased, adding that the colour was something those at the company "jealously guard".
In his ruling, Allan James, the registrar, said the colour purple had built a distinctive character associated with Cadbury. He rejected claims that Cadbury had registered the colour in bad faith as absurd.
Fiona McBride, a partner at Withers & Rogers, described the decision as a "major relief" for Cadbury, saying its use of the colour was now "iron-clad and the brand will be unlikely to face further challenges over the use of the colour purple in the future".
Cadbury was, however, limited to using the colour on chocolate bars and chocolate drinks. It had not proved such distinctiveness in all confectionery, James said, such as Roses chocolates.
McBride said: "Colour registrations are notoriously difficult to obtain, largely because it can be difficult to prove sufficient use to demonstrate that the colour has become synonymous with the brand in the mind of the consumer."