From the Western Morning News (and I'm sure we'll see more of it elsewhere): Scientist sums up perfect Christmas: "A university mathematician has calculated a formula for the perfect Christmas - and it includes plenty of food and drink. Professor Rudi Dallos, from the University of Plymouth, has analysed what makes Christmas swing and produced the above equation".
You can see the formula at the original press release from the Cake Group. It's in aid of promoting a booklet from the Children's Society, Batteries Not Included, giving hints and tips for celebrating Christmas economically. It's in a good cause and can be defended as being lighthearted in intent.
Even so, this is a standard news story format - Google scientists formula perfect and see Formula for the perfect formula - based on the discovery, usually in some promotional context, of a claimed formula (often, as in this case, mathematically malformed) for some commonplace situation. It trivialises mathematics in the popular eye, and academics really ought to consider its effect on the reputation of their field before they sell out to this kind of fluff.
It's usually enlightening, when you see these formula stories in the press, to check out of the background and see who is trying to sell you what. This story is at least open about its agenda, but this is not always the case. For example, for the much-publicised "perfect bacon butty" story that appeared earlier this year, it's easy to find that this isn't some kind of blue-sky food science research at the University of Liverpool (as you might naively expect from the BBC's Scientists' 'perfect' bacon butty). The bacon research was conducted at the Food Chain Centre of Industrial Collaboration ("delivering the power of science to food and drink companies since 2004") and unsurprisingly commissioned by Danish Bacon.
Such checks are general good advice with "scientific discovery" stories. They can be genuine academic interest stories, but often they hide situations where even the researchers turn out to be selling the product the story reports. News reportage is lax if it fails to identify such a conflict of interest.