A headteacher of a Lancashire private school is recovering at home after it is thought bleach was thrown into his face.

Jim Keefe, head of Arnold School in Blackpool, was attacked with the substance yesterday morning when he opened the door of his home which is close to the school grounds.

He was taken to hospital but released the same day and is now helping police with their inquries into the incident at 7am yesterday.

A police source confirmed that one line of inquiry was it may have been a revenge attack over the recently confirmed merger between Arnold School and King Edward VII & Queen Mary School in Lytham St Annes.

Parents of pupils at both private schools raised concerns about the move as numerous Facebook campaign groups against the amalgamation were set up.

The Charity Commission was called in to look at the objections and last Friday ruled that the proposed Arnold KEQMS School - with Mr Keefe as head - would open in September 2012.

A spokesman for Arnold School said: "An incident took place yesterday morning which the police are investigating.

"Mr Keefe is back working at home and, as you would expect, normal school life has continued both yesterday and today."

In a letter sent to parents and staff, chair of governors Jerry Wooding wrote: "As you would expect, the police have been fully involved and are investigating what occurred.

"It would not be appropriate for us to comment any further at this stage but please be assured that we have no reason to suspect that this was anything other than an isolated incident.

"I know that you will join me in sending Mr Keefe and his family our best wishes."

A spokesman for Lancashire Constabulary said: "Police inquiries into the incident are continuing.

"We are appealing to anyone with information to come forward."

Founded in 1896, Arnold School, which caters for children aged two to 18, was taken over in 2008 by the United Church Schools Trust (UCST) - whose chairman is former Archbishop of Canterbury Lord Carey of Clifton.

Former pupils include Jaguar Cars founder Sir William Lyons, Nobel Prize for Chemistry winner Dr Michael Smith, former England footballers Jimmy Armfield and George Eastham, ex-England cricketer Tom Graveney, TV presenter Peter Purves and Pet Shop Boys star Chris Lowe, according to the school website.

KEQMS was run by the Lytham Schools Foundation, which dates back to a flood disaster in the town in 1719 when a relief fund was set up. Its motto is Sublimis ab unda - raised from the wave.

The fund's trustees decided to establish a grammar school for boys almost 200 years later and King Edward VII School was opened in 1908. Queen Mary School for girls followed in 1930.

The school is now co-educational with pupils also aged from two to 18.

The amalgamation means that Arnold School will close its doors as it moves to the KEQMS site Earlier this month, the Times Education Supplement reported the controversy that followed the announcement of the merger two months ago.

It said "outraged" parents at KEQMS had gained the support of more than 80% of the staff who were also said to be opposed to the move.

The article added that senior teachers at KEQMS told governors the plans had led to "a crash in morale" among staff.

They were said to have accused UCST of not inspiring confidence "to act in the best interests of all those concerned with our school".

In October, Lord Carey wrote to parents and staff at both schools to give reassurances about the merger.

He said that, like the Lytham Foundation, the not-for-profit UCST was a Christian educational charity and that "our values and ethos are very similar".

He wrote: "Despite the pressure we have been put under by those opposed to the merger, our commitment remains steadfast.

"We are all very clear that this is a merger between the two schools with each bringing its own strengths to the table. We stand firmly behind our commitment to make it succeed."

He added UCST had decided to remain "calm and focused" on the merger planning in the face of "personal attacks and false information perpetrated by those who are intent on wrecking the merger".