Police are now urging people to turn cold callers away from their doors and to look into the introduction of No Cold Calling Zones in their neighbourhoods.
The theft took place at around 11am on Tuesday 16th August in Woodland Avenue, Gainsborough, when a man claiming to be selling cleaning products knocked on the door of an 80-year-old man.
The pensioner refused entry, but the offender pushed past him and entered the house anyway.
While the occupant was arguing with him, another man entered the house before the thieves stole a cash box containing more than £100.
The victim, who is in poor health, was shaken but not hurt, and thinks one of the offenders may have visited his house around six weeks before – again offering cleaning products for sale.
The first offender was white, between 25 and 30-years-old and around 5ft 10in tall.
He was of medium build and possibly spoke with an Irish accent.
The other man was white and around 5ft 3in tall and stocky, with a fat face. He had grey receding hair and a goatee beard.
Lincolnshire Police are appealing for anyone with any information to get in touch with them as soon as possible, while residents are being urged to never let anyone cold-calling into their homes.
They are being advised to call the police immediately with descriptions of the suspects and any vehicles they are using as these incidents are treated as a top priority and officers will attend promptly.
If you wish to set up No Cold Calling Zones, which make it clear to potential offenders that the police will be called after any attempt to cold-call, then you can contact your local beat team via the non-emergency number on 0300 111 0300.
To find out more about the how to protect elderly and vulnerable people in your area, you can contact the Doorstep Crime Partnership via Sgt Caroline Broughton of Lincolnshire Police on 01522 558481, or Trading Standards on 01522 782341.