More than 200 disappointed families were not offered a primary school place from any of their five choices yesterday, with 76 children left without a school place at all.
Merton Council has admitted it has struggled to cater for the rising number of children in the borough, despite investing millions in their primary school expansion programme.
Yvette Stanley, director of the council's children, schools and families department, said: "Demand for primary school places shows no sign of slowing down as we continue to accommodate children at schools which are local to their home.
"Over the past decade we have seen the birth rate in Merton increase by 39 per cent and that is not including the families moving into the borough who also need primary school places."
Applications were up 179 from last year, leaving the council with 2766 children to allocate places.
Councillor Martin Whelton, cabinet member for education, said: "Sixty places were expected at Park Community School, which may or may not open in September, and 30 places at Dundonald."
"We expected we could have another class at Dundonald but unfortunately it's gone on longer than we had hoped for."
Park Community Free School has secured a permanent site at Tyndale House, Dorset Road, which they hope will be fit for purpose by September 2015, but is still searching for temporary buildings so it can open this September.
Parents hoping to send their children to the Christian free school received a letter yesterday advising them to accept an alternative school place until a site is found.
A spokeswoman for Chapel St, a Morden-based charity which runs the school, said: "The site is not something we have a decision about, that's the Department for Education."
In central Wimbledon, where there is the highest demand for primary school places, the Protect Dundonald Rec campaign group has delayed council plans to create 210 extra school places with a new two-storey extension which will be built on their much-loved park and children's playground.
Coun Whelton said the council is in discussion with school governing bodies to find 60 more places by the end of the month.
He expects the remaining 16 places to be filled from children not accepting places or moving out of the borough.
The situation drew criticism from the opposition Conservatives
Councillor James Holmes, Conservative education spokesman, said: “I recognise it’s a challenging situation that the administration is trying to grapple with but I do think they have made a number of errors.
“Had the administration had a more proactive attitude to Park School they could have found accommodation sooner.
“It’s all very well blaming Dundonald but it’s very controversial, it’s been controversial for years and rather than just standing there and saying it’s Dundonald’s fault, the administration could have looked for alternative accommodation.”
Full advice was given to parents in rejection letters about how to move forward and the council has said it is committed to finding every child a reception place for September.
With numbers of applications expected to rise by a further 180 in 2015, the council has committed £85m towards school expansions over the next four years.
Twenty primary schools have been earmarked for expansion to provide more than 4,400 new primary school places in 21 new forms of entry by 2018.