'Hollow' strawberries.

As a full-time gardener I'm often asked for advice on many things garden related and I'm always happy to help out, but this one has got me stumped.
I was asked by someone at work the other day if I new the reason for this.
She has been growing strawberries at home in large containers.
From what she tells me they are well fed, watered etc. and are producing plenty of decent sized fruit. However, when cut open there is apparently very little flesh inside, they are effectively 'hollow'.
She couldn't remember the variety.
Is this simply a characteristic of some strawberry varieties or is there some other explanation here?
Any ideas? My reputation at work could be on the line here! :o

 

Sounds like too much watering and feeding Trunky. Some commercial varieties can be hollow, supermarkets being more concerned with appearance than quality.