The officers attended the man's house after two men allegedly scammed him out of £3,500 after telling the victim his fencing needed replacing.
While the elderly man had gone to the bank to take out cash for another instalment for the men, officers arrested a suspect waiting at his home.
PCs Lyndsey Wright, Chris Groome and Lukasz Dmitruczak noticed the victim's garden fencing was not secure so they came up with a plan.
During their day off on Monday, April 3, a week after the incident, 10 officers returned to the victim's house and replaced the fencing and even tidied his garden, which the victim struggles to maintain.
Working from 10am until 8pm, PCs Wright, Groome and Dmitruczak were joined by PCs Thomas Ciotti, Amy Harding, Harinder Khella, Shalinder Panesar, Ayesha Razzaq, Joseph Thwaite and Fahrettin Togluk.
The team did not quite finish their work during the day, so on Sunday (April 9), PCs Groome, Dmitruczak, Panesar and Thwaite returned before their night shift to finish the job.
This is not the first time PC Panesar has hit the headlines after he was given an award from the Metropolitan Police Commisioner for rushing into a burning buidling.
Posting on Facebook on April 3, Hillingdon Police said: “Officers from emergency response team four showed real heart.
“One of the officers, PC Groome, was concerned about the state the gentleman's fence had been left in and decided further help was needed.
“On their day off, several of the officers have visited the elderly gentleman and are erecting the new fencing for him.
“Very well done ERT4. We are proud of you."
The materials for the work were donated free-of-charge by B&Q DIY store in Glencoe Road, Hayes.
Police said an investigation into the alleged scam is ongoing.
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