A knifeman robbed a mother with a child before targeting a 75-year-old man moments later.

The thug threatened the woman with a large knife, forcing her to hand over cash.

About 15 minutes later the man pushed a pensioner as he withdrew money from a cashpoint in by the post office in Woodgrange Drive, Southend, snatching his cash.

A Post Office worker said: “The man is a regular customer in our shop, he came in quite shaken and we called the police for him.”

Councillor Mark Flewitt, Southend councillor for public protection said: “It is horrendous that this has happened.

“This time of year the evenings are dark and people must be careful not to carry too much cash with them leading up to Christmas.

“Let’s just hope that anyone with any evidence comes forward. It is absolutely inexcusable that this should happen.

“A town should have so many measures to make people feel secure but if someone has got the intent to do something as cowardly as this, it’s difficult to guarantee that this wont happen.

“Police must have full co-operation from people and hopefully there will be some CCTV that captured the incident.

“It is hideous to do this to someone whether old or young .

“My thoughts go out to the victims and hope they get over this.”

A spokesman for Essex Police, said: “A man has been arrested in connection with investigations into two robberies in Southend on Wednesday, December 19.

“A 31-year-old woman was approached by a man in Woodgrange Drive at 4.25pm. He demanded money and threatened her with a large knife. She handed over money and he left the scene. Just before 4.40pm, a 75-year-old man was withdrawing money from a cash machine outside Woodgrange Post Office, in Woodgrange Drive.”

A 40-year-old man has been arrested and is being questioned.