This takes the total number of organisations registered with the Electoral Commission to 37, all but four of which did so since the lobbying act gained royal assent a year ago.
The act says that, in the run-up to elections, charities, individuals or other groups spending more than £20,000 in England or £10,000 in other parts of the UK on particular "regulated activities", and if those activities might "reasonably be regarded as intended to influence voters", must register with the Electoral Commission as non-party campaigners. The first regulated period under the act began on 19 September.
The ISC is an umbrella group for eight associations of independent schools, their heads, bursars and governors, and together represents more than 1,200 independent schools in the UK and overseas. It is not itself a charity, but is a not-for-profit organisation – although some of its members are charities. One of its five strategic objectives is "to protect and promote the sector through targeted, focused and effective campaigns with policy-makers and opinion formers".
Sunena Stoneham, principal legal counsel at the ISC, said: "The run-up to an election is by definition a fast-moving and fluid period, and while the ISC does not support any particular political party, we need to be free to comment on or lobby on issues that are relevant to our schools. The ISC has registered with the Electoral Commission as a precaution so that we can continue to protect and promote our schools through targeted, focused and effective campaigns without falling foul of the law inadvertently."
The charitable status of independent schools has been in the spotlight in recent years. In 2011, after a challenge by the ISC, the Upper Tribunal ruled that the Charity Commission should withdraw part of its guidance on public benefit.
The issue returned to the party political arena in November last year, when the Labour Party said it would introduce a requirement for private schools to support their state counterparts or face losing their business rate relief.
Of the 37 organisations to have registered as non-party campaigners, six are charities, the most recent being the RSPCA, which registered in November and had to set up a separate legal entity to do so, and Hope not Hate Educational, which is registered with the Charity Commission as the Searchlight Educational Trust, and is the charitable arm of the campaign group Hope Not Hate, registered in December.