Schools are considered to be under-performing if fewer than 64 per cent of pupils reach the expected standard in reading, writing and maths.

64 per cent is the national average and therefore the benchmark schools have to beat.

In 2018, 4,323 pupils in Dorset sat took the end-of-primary national curriculum tests but just 60 per cent of pupils achieved the expected standards in the three key areas.

This compares with 71 per cent in inner London which was the best performing area.

Girls in the county far out performed the boys with 64 per cent reaching the expected standard compared to 56.

A spokesman for Dorset County Council (DCC) said improving the county's primary performance was now a "priority".

"The local authority will continue to work with maintained schools to drive up the standards at KS2 for reading, writing and maths.

"The results at KS1 and KS4 have shown encouraging improvement in the last twelve months and we now want to see the same at KS2. This will also be a priority for the newly formed Dorset School Improvement Board," the spokesman said.

She added as part of the council's improvement strategy DCC was working in collaboration with their partners in schools in part through the Improvement Board and the current focus was to improve maths at Key Stage 2.

"Improving outcomes of pupils is a priority for Dorset and this has been reflected in some part in the decline in Ofsted ratings, particularly the disappointing drop in the number of outstanding schools. DCC has robust strategies in place to secure improvement, and many schools are making rapid progress.

"We celebrate the success of many pupils and Schools across Dorset and we are committed to ensuring that standards rise and all are schools are judged as good or outstanding," she said.