In the Kent seaside town of Whitstable, long-term residents call them DFLs – people who have moved “down from London”, sometimes for the lifestyle but more often for cheaper housing.

The number of people fleeing the capital to live elsewhere has hit a five-year high. In the year to June 2016, net outward migration from London reached 93,300 people – more than 80% higher than five years earlier, according to analysis of official statistics.

A common theme among the leavers’ destinations is significantly cheaper housing, according to the estate agent Savills, which analysed figures from the Office for National Statistics and the Land Registry.

Cambridge, Canterbury, Dartford and Bristol are reportedly among the most popular escape routes for people who have grown tired of London and its swollen property prices.

The most likely destination for people aged over 25 moving from Islington is St Albans in Hertfordshire, where the average home is £173,000 cheaper. People moving from Ealing to Slough – the most popular move from the west London borough – stand to save on average £241,000. Among all homeowners leaving London, the average house price was £580,000 while the average in the areas they moved to was £333,000.

The exodus is not just of homeowners, but of renters too. Rents in London have soared by a third in the last decade, compared to 18% in the south-west, 13% in the West Midlands and 11% in the north-west of England.

The only age group that has a positive net migration figure in the capital is those in their twenties, the research found. Everyone else, from teens to pensioners, is tending to get out. Since 2009, the trend has been steadily increasing among people in their thirties with 15,000 more people in that age bracket leaving every year than at the end of the last decade – a 27% rise.

The phenomenon is being driven by a widespread desire to “trade up the housing ladder”, something that is all too often impossible in London according to Lucian Cook, Savill’s head of residential research.

“Five years ago people would have been reluctant [to move out] because the economy wasn’t as strong and some owners didn’t want to miss out on house price growth [in London],” he said.

But with increased employment opportunities outside London and property prices levelling off in the capital, people are becoming more confident to make the leap, he said.

The trend is particularly affecting public servants, according to teaching and healthcare unions.

“Teachers who can find a job elsewhere move out,” said Martin Powell-Davies, London regional secretary of the National Union of Teachers. “There’s a high turnover of staff in London caused in part because they can’t afford to live. That creates instability for the pupils. They build up a relationship with their teacher and the next year that teacher will be a different person.”

Andy Winter, 38, a secondary school teacher in London has managed to stay in the capital because he started living on a canal boat four and a half years ago.

“My experience is that [housing] is completely unaffordable,” he said.

Winter balked at paying a £1,000-a-month mortgage and started living on the water. From September, he will pay £80 a month to moor his £10,500 boat near his new school in Hayes, west London.

Nurses, care workers and social workers are among those “being forced to live outside London and commute for longer” according to Christina Mcanea, assistant general secretary of the public service union Unison.

“The danger is London will start to lose these staff” she said. “Turnover rates in some parts of London are already 30%. People do it for a while and then the commute gets too difficult an experience.”

Unison has urged the government to allow the public sector to start repurposing redundant buildings as staff accommodation rather than selling them off for private housing.

However, despite the figures, London is not shrinking. The Savills research does not account for flows of migration abroad (a net increase of almost 100,000 between 2011 and 2015) and new births in the capital far outweighing deaths, that continue to push the population up towards 10m. It is expected to expand from its current 8.7m population to 9.8m by mid-2025.

‘It is nice to have somewhere we enjoy being in’

Ellie Russell, a former science teacher, and her husband, Colin Stratton, who works in IT, moved from Leytonstone to Southend-on-Sea last year with their eight-year-old daughter and two-year-old son. The couple had been looking to buy in east London, but could only find two-bedroom flats for around £300,000.

Ellie Russell, Colin Stratton and their two children moved to Southend. Photograph: The Guardian

“We were renting and I was pregnant with my son and we wanted a bigger place,” Russell said. “The rent was crazy to get a three-bedroom place and while we had a deposit and were looking to buy, prices went up about £60,000 as we were doing so. We could have got a two-bedroom flat if we had pushed the boat out.“

So they took the plunge to move to Southend in Essex and bought a c1900 three-bed house with a garden for £230,000.

“It was difficult as we didn’t know anyone in Southend,” she said. “But it is nice to have somewhere we enjoy being in. Now there seems to be quite a few people moving from London to Southend.”