Mark Towson, 52, took the money from his clients, a 91-year-old woman and her husband who suffered from dementia, to pay off his own debts.
The Herald Scotland reports Towson, who still denies taking the money, was sentenced to five years in prison at Paisley Sheriff Court on Friday.
He was found guilty of the crime at an earlier hearing.
It was earlier revealed that Townson of Baillieston, Glasgow, had worked for L&G for 18 years, dealing with clients throughout Scotland and in Northern Ireland.
He advised the couple, Mr and Mrs McDowell, for ten years until 2013.
The couple had a £1.4m nest egg, with Mr McDowell, a former pilot, receiving a pension of £50,000 a year.
Between January and October 2011 Townson, an ex-professional cricket player in Australia, took £385,090 from the McDowells savings, the court heard.
In December 2012 he took another £80,000, at which point he was caught by his branch manager and suspended pending an investigation.
The former adviser said he was in “a desperate financial situation” caused by him supporting two other households as well as his own, that of his ex-wife and university student son.
He also owed money to family members as he had spent their share of his mother’s inheritance.
When caught, Townson claimed the money had been given to him as a gift, a claim Mrs McDowell denied.
