Five men have been jailed for their roles in a scam which invited dozens of elderly people to invest in property near the Olympic site in east London.
They conned their victims into buying fake or worthless shares, claiming land would "rocket" in value before 2012.
They received £286,000 over a seven-month period in 2006 and 2007, Southwark Crown Court was told.
The "outrageous and elaborate" fraud hit those "who could ill afford to lose money", Judge Stephen Robbins said.
Adrian Davison, 43, of Chislehurst, Kent, masterminded the scam and was sentenced to seven years after admitting four counts of conspiracy to defraud.
Derek Voysey, 64, of High Wycombe, Buckinghamshire, was given 18 months, having been convicted of one count of conspiracy to defraud following a trial last September.
Patrick Golding, 40, of Kilburn, north-west London, and Kenneth Mullen, 42, of Larkhall, South Lanarkshire, both pleaded guilty to one count of conspiracy to defraud.
Golding was jailed for 20 months and Mullen was sentenced to 30 months.
Another man - Andrew Bingham, 71, of Rye, East Sussex - also admitted one count of conspiracy to defraud and is due to be sentenced separately.
Christopher Fay, 64, of Blackheath, south-east London, pleaded guilty to one count of entering into an arrangement - money laundering - and was jailed for a year.
The "boiler-room" scam involved the men using pressurised selling techniques, City of London Police said.
Their promotional material included quotes supposedly from London 2012 chief Lord Coe talking about opportunities for development in east London.
Some of the victims told the BBC last year how they were conned out of tens of thousands of pounds.