The legal battle over the use of the McAlpine family name turn nasty in court this week, with Sir Robert's branch of the tree claiming that Alfred's "poor payment record" would reflect badly on the older firm
What's in a name? Quite a lot if you belong to the McAlpine dynasty. After happily co-habiting in the building industry for 80 years the two famous McAlpine firms - Sir Robert and Alfred - are in danger of falling out over who has the right to go by the M-word.

The firms have enjoyed a harmonious relationship since Alfred McAlpine left his father's company Sir Robert McAlpine in 1934 to set up on his own. But a spat developed when the Alfred firm decided to rebrand itself McAlpine last October.

You would have expected any family tiff between the publicity-shy McAlpines to have been settled behind closed doors, but this week both companies appeared at the High Court as Sir Robert McAlpine attempted to win an injunction stopping Alfred from rebranding. It is also suing for damages.

In court, Malcolm McAlpine, a grandson of Sir Robert, claimed that the rebranding exercise would confuse the industry and potentially tarnish Sir Robert McAlpine's reputation, if people were to think that Alfred was the same company as Sir Robert. Malcolm McAlpine said that the services sector in which Alfred operates is much more volatile than contracting, where Sir Robert does the majority of its work. He said that a Jarvis-style downturn in fortunes for Alfred McAlpine would also reflect badly on Sir Robert.

Alfred is contesting this "passing-off" argument – and has good financial reason to do so. It has already spent £400,000 on rebranding and it would cost around the same amount to revert to the original branding on buildings and vehicles. Were the legal costs also to be included, one Alfred McAlpine insider estimated that the company could lose up to £2m if the injunction goes ahead.

Although the argument may have started as a mere tiff, it is in danger of turning into something much more damaging. In the High Court this week Sir Robert McAlpine called on demolition contractor Keltbray to question the reputation of the publicly owned Alfred McAlpine. Keltbray managing director Brendan Kerr said that Alfred had a reputation for wrangling over terms and accused it of having a "poor payment record".

It's clear that any family goodwill that remained between the firms has all but disappeared. You can be sure that these distant relatives won't be paying each other a visit next Christmas.