Dogs may be man’s best friend, but the British are also a nation of cat lovers — so there was widespread shock at images of the footballer Kurt Zouma kicking and slapping one of his cats.

The 27-year-old West Ham and France defender issued an apology, saying that he was “deeply sorry”, and insisting that the cats at his home in Essex were “loved and cherished”. Though his manager still selected him to play, the club fined Zouma £250,000 — two weeks’ wages — and donated the money to an animal charity.

The RSPCA confiscated his cats and more than 300,000 people signed a petition calling for the footballer to be prosecuted. Essex police confirmed that “urgent inquiries” were under way in conjunction with the RSPCA.

The case has put a spotlight on the charity, which has since its foundation in 1824 been the body that prosecutes most people charged with animal welfare offences. It came into existence before the modern police force or Crown Prosecution Service (CPS).

It now undertakes private prosecutions in 85 per cent of cases brought in relation to cruelty to animals under the Animal Welfare Act 2006.

Its success rate is high, but figures from the charity suggest that the number of prosecutions it undertakes is falling. In 2019 its prosecutions resulted in 1,432 convictions in the magistrates’ and crown courts — a success rate of nearly 94 per cent. While in 2020 it secured 633 convictions, with a success rate of slightly more than 90 per cent.

The RSPCA justifies its prosecutorial activity on the basis that it fills a gap in the provision of public service, meets its charitable objectives and is an experienced prosecutor.

Criticisms prompted the charity to commission an independent review of its prosecution role in 2014, conducted by Stephen Wooler. In response to the review’s 33 recommendations, the RSPCA committed to make changes within 18 months.

However, in 2016 MPs on the environment, food and rural affairs committee criticised its slow progress in implementing the reforms. The committee also concluded that the combination of its investigative, campaigning and fundraising activities gave rise to “a conflict of interest” and recommended that it should withdraw from acting as a prosecutor of first resort where there are statutory bodies with a duty to carry out the role.

In 2020 the justice committee’s inquiry into private prosecutions received submissions that were critical of the RSPCA’s prosecutorial activities. The Countryside Alliance suggested that it was inappropriate for the RSPCA to remain the principal prosecutor of animal welfare offences, and John Goodwin, a defence solicitor at Cohen Cramer Solicitors, highlighted concerns over the way it carried out its role.

Defending itself, the RSPCA says that it follows the guidance set out in the CPS code for Crown prosecutors and applies the same two tests — sufficient evidence and public interest. It has also put in place additional safeguards to ensure transparency, review and redress. The RSPCA also joined the Private Prosecution Alliance, which states that it is committed to uphold high standards of investigations and disclosure, and follows the code of private prosecutors.

A year ago, the charity announced that it planned to stop prosecuting, continuing only with investigations. A spokeswoman explains that its new strategy was the result of “a number of changes to society and legislation and the wider world in which we operate”. Changes included the increasing complexity of cases, with many involving organised criminal gangs and fraud.

Passing the prosecutor role to the CPS, says the charity, frees up its resources to focus on its rescue, investigation and care work where it can make the most difference to animals.

Last summer the law changed to increase the maximum sentence for animal cruelty from six months to five years — a move that increased the charity’s desire to hand over the role.

However, a year later the RSPCA is still prosecuting and says that the transfer is unlikely to happen quickly because of the government’s focus on the pandemic and Brexit. An RSPCA spokeswoman says that discussions about the handover are continuing with the CPS, the attorney-general’s office and other relevant officials.

She says there are “no agreed timelines” and that the charity has made a commitment “not to step back from our prosecution work until the resources and expertise are in place elsewhere”.

A CPS spokesman said: “We are aware the RSPCA is reviewing its prosecution function,” adding, “any proposed change to legislation in terms of which investigative bodies are able to refer cases to us is a matter for the government.” Transferring the responsibility for prosecuting to the CPS, he said, would require an amendment to the Prosecution of Offences Act 1985 or an assignment from the attorney-general.

Private prosecutions have come in for wider criticism in the wake of the Post Office scandal. A public inquiry into the prosecutions brought by the Post Office, which led to the wrongful convictions of hundreds of sub-postmasters and mistresses, began this week.

Elsewhere, a judge criticised a law firm and an animal rights charity for unfairly bringing unmeritorious private prosecutions against individuals regarding alleged offences around the sale of puppies.

Stuart Nolan, the managing director of DPP Law, a national criminal defence firm, says transferring the responsibility would put an “additional burden” on the “overstretched” CPS.

He suggests that compared with prosecuting murder, rape and terrorism cases, “animals would be low in the pecking order”, which would lead to a reduction in prosecutions and undermine justice.