Some 2 million have cut working hours and upped spending to help grandchildren as work pressures increase, say charities

A 'hidden army' of grandparents have stepped in to help families who cannot afford mounting childcare costs, with nearly 2 million of them in Britain giving up work, reducing their hours or taking time off to do so, charities said on Tuesday.

They are also spending significant sums in financial support to their grandchildren, according to a poll. Those grandparents who provide most childcare are also most likely to help with money too.

The findings are based on a poll for Grandparents Plus, Save the Children and the Family and Childcare Trust in the wake of what the trust says is a 27% rise in childcare costs in five years.

The bank of gran and grandad may be contributing as much as £8bn each year to bridge the gap as work pressures increase, claim the organisations following a face-to-face poll of 2044 adults they commissioned from Ipsos Mori. In all, 617 of those questioned described themselves as grandparents or great-grandparents.

The poll suggests 14% of grandparents have cut their working hours, given up jobs or taken annual or sick leave to care for grandchildren at some point in their lives. More than one in eight grandparents say they have spent more than £1000 on their grandchildren in the past 12 months.

Grandparents who spent time caring for grandchildren are more likely to agree benefits for children should be protected, with 88% agreeing, compared with 67% among grandparents who do not offer such family support. Wider public support for spending on the basic state pension and benefits for older people to be protected (also 88% in the poll) fell to 54% if that happened at the expense of children.

Sam Smethers, chief executive of Grandparents Plus, said the poll also showed public support for finding ways to ease pressure on grandparents, including unpaid leave.

She said: "This is generation generosity in action... It suggests we need to rethink working requirements for the ageing population, who are being expected to work longer and care for more grandchildren. This simply is not sustainable."

Save the Children warned that many parents on low incomes were already being priced out of formal childcare and were left with no option but to quit work or rely on friends and family.

Bobby Duffy, managing director of public affairs at Ipsos Mori, said the survey "illustrates very clearly that the idea of there being a 'war' between generations is very far from the day-today reality for most people. In fact, it is the opposite – it shows how many young people rely heavily on grandparents for support".

He added: "This puts pressure on grandparents – who often have limited resources themselves – and those families who don't have grandparents with time or money to miss out on this vital source of support."