But, just four weeks into the job, the 54-year-old was so shocked by what he saw as a total breakdown in pupil behaviour that he asked to be moved.
During his month at Southwark junior, Mr Pearson claims that children urinated on the stairs, visited sex websites during information technology lessons and hurled missiles at teachers in class.
The 376-pupil school was placed on special measures in September 1999 after inspectors concluded that it was failing to provide an acceptable standard of education.
Weaknesses recorded by the Office for Standards in Education included deteriorating pupil behaviour, low academic attainment and poor teaching.
Inspectors have since observed significant improvements but Mr Pearson, now working as a supply teacher in Leicestershire, said: "In all my years teaching, including time in an extremely challenging school in London, I have never experienced anything like this."
He worked at the school in January and said: "The kids were completely out of control, spitting, shouting and trampling on desks. Teachers were regularly threatened. One was struck above the eye while I was there and narrowly missed losing her sight.
"Children had to be escorted to the toilets with a monitor to prevent vndalism. On one occasion, I even noted puddles of urine on the school stairs.
"Teacher-training days are taken up with self defence and (guidance about) how to restrain violent children."
However, others do not echo Mr Pearson's account of events at the school.
Nigel Turner, the secretary of the local branch of the National Association of Schoolmasters Union of Women Teachers, said the school had staffing difficulties, but that he had received no complaints from members about children's behaviour.
The council, headteacher and governors acknowledged that the school had been through a "rough patch", but said it was improving and should be out of special measures by the end of the year.
Alisa King, Southwark junior school's chair of governors, said: "The lurid picture painted by Mr Pearson is quite simply not one we recognise at all.
"This clearly isn't the same school that the HMI inspector praised last week for the considerable progress being made under the able leadership of its new head.
"His (the headteacher's) comments made it clear that we are getting to grips with challenging behaviour as well as raising standards.
"Mr Pearson plainly found his task at an inner-city school a difficult one and was given unstinting support by his colleagues, the head, and the council.
"I'm only sorry that he didn't raise his apparent detailed concerns with any of them."