The closure of the Welsh-medium school in Dinas is part of the local authority's policy to improve education in the area.
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My son says to me mummy please don't send me to a big school
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Parent, Vicky Williams
The majority of the 18 pupils taught at the site will start next term at Ysgol Bro Ingli in nearby Newport.
Mother-of-two Vicky Williams has campaigned to keep the school open for her eldest child four-year-old William.
"My son says to me 'Mummy please don't send me to a big school'.
"When they are four it is a big shock when they are sent to a big school," she said.
Pembrokeshire council say the closure is a move towards equality of education for pupils across the region.
Under the plans Molyegrove school, near Cardigan, will also close in July 2003 and a new £1.2m facility will be built in St Dogmaels.
The new site, which is due to open in September 2003, will cater for up to 140 pupils aged from three to 11.
Earlier this year parents from both schools unconvinced about the benefits of the education shake-up took their protest to the National Eisteddfod in St David's.
Ms Williams said they have also held demonstrations locally: "We have sent letters we have walked through the village of Dinas protesting and we had a lot of support from the village.
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We are not doing anyone any favours by burying our heads in the sand
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Pembrokeshire council John Davies
"My main concern is that when you have a small school you keep the community spirit alive.
"But when there is no school then no one will be meeting to discuss any issues.
"We have a little shop, post office and a petrol station but if you take away our school you take away our central point."
The council claim that figures from the health authority show there will be a significant drop in the number of pupils in the next three to four years.
Pembrokeshire council's cabinet member for education, John Davies, said: "We are looking at a drop in pupils numbers of about eight to 10% and we have to prepare for that.
"We are not doing anyone any favours by burying our heads in the sand.
"We have to face these problems head on and that is what we are doing in Pembrokeshire by providing a better and new education facility for our next generation."