Is this the moment that UK shale starts to be taken seriously? Of course, viewed from Downing Street, the industry is already very serious. Tax breaks are being prepared and the chancellor has hailed shale as "part of the future". It's just that the UK scene is populated by small companies making eye-catching projections about potential reserves before hard-headed assessments can be made of the likely rates of profitable recovery.

The arrival of Centrica, which is buying a 25% stake in the Bowland Shale exploration licence, improves the picture. The presence of a big player sends a message that UK shale may indeed develop into a big story. Or, at least, that's the theory.

It would be useful to know, though, how much optimism and enthusiasm Centrica really has. The company has stood outside the well-developed US business and chief executive Sam Laidlaw said in January that UK shale would not be "the game-changer we've seen in North America". He offered two reasons why. First, a lot of UK shale sits underneath large towns and cities. Second, unlike in the US, landowners don't have the same incentives to encourage fracking since the shale belongs to the Crown.

So what's Centrica up to? Covering its backside would be one interpretation. The UK's biggest gas company would look silly if it stood on the sidelines as shale became a success. And it wouldn't score any brownie points with the government by pondering for too long – saying "no" to new nuclear is one thing; taking a back seat on shale might look unco-operative.

A more positive spin is that Centrica is sensibly buying an option on shale for pin money. It is paying £40m to Cuadrilla, the UK firm chaired by Lord Browne, and AJ Lucas, an Australian outfit. It will also contribute £60m for exploration and appraisal. In the context of a group-wide annual capital expenditure budget of £1.5bn, that's next to nothing.

We shall see. The shale industry's future will become clearer only once it moves beyond the current phase of extracting interesting seismic data and starts putting a price on production. That's when the economics will be clarified, and when the tricky question of dealing with local objections to fracking will have to be confronted.

Centrica's investment takes the story on, but the broad picture remains unaltered: shale should be explored, but you wouldn't want to base your energy policy on it just yet.