In the aftermath of the fire at Notre-Dame in Paris, luxury, beauty, energy and finance companies pledged hundreds of millions of euro to the cathedral's restoration. 

While this is not focused PR, it will enhance the reputation of those companies, according to an expert in business ethics and corporate social responsibility.

Dr Eleanor O'Higgins, from the Smurfit Business School, described the pledges as a spontaneous act of philanthropy.

"I think these businesses didn't have a big marketing campaign, that it just happened spontaneously. It happened very quickly so it couldn't have been deliberative planning," she said.

"It can do good for the companies. I don't think that a company with a really bad reputation and who is doing bad things, that this would enhance their reputation. It would just be seen as PR," Dr O'Higgins said. 

"I think good companies will enhance their reputation through this kind of action," she added.

People are not likely to buy a Gucci bag today just because the owners of the brand are supporting the restoration project, Dr O'Higgins said, but there is a now a positive association with those brands.

"They will be in their minds now. It almost adds a halo to their products," she stated.

She said companies could get a long-term rolling benefit as opposed to the benefit you might get from a deliberate marketing campaign. 

"This is not focused PR, but it enhances reputation," she added.