A primary school has been branded "inadequate" just four years after inspectors hailed it as one of Croydon's best.

Parish Church Junior School, in Warrington Road, plummeted from the best rating to the worst in an Ofsted report published days after it expanded to accept more pupils.

The primary opened for the September term last week with 30 extra reception children as part of Croydon Council's bid to tackle a school places crisis.

In a report published on Friday, inspectors said pupils' achievement, teaching quality and leadership and management were all inadequate and warned the behaviour and safety of pupils required improvement. 

Inspectors rated the school "outstanding" following their last visit in May 2010.

But the latest report, following an inspection in June, said: "Achievement is inadequate because too many pupils significantly underachieve, particularly in reading and writing.

"Pupils supported by additional funding do not progress as well as others in the school and the gap is widening."

The report added teachers' expectations were not high enough and also highlighted the marking of work and tracking of pupils' progress for criticism.

The school's headteacher, David Morgan, left in July to be replaced by Wendy Jacobs.

The school declined to comment, but a Croydon Council spokesman said: "The council has worked with the Southwark Diocesan Board of Education to appoint an experienced head teacher with a proven track record to replace the former head who left at the end of last term.

"We have also helped provide additional teaching and learning support from two outstanding practitioners on a weekly basis. 

"We believe the school now has sufficient capacity to make rapid progress and we’re satisfied with the actions they have already taken."

The school permanently expanded from 90 to 120 pupils in each year, beginning this term.