Robbed of his prized watch by knife-wielding moped riders, Derek Saunders was left heartbroken.

The 60-year-old was out for a walk along Southside Common on September 15 with his grandson Cooper when two men pulled out knives and threatened the pair.

No one was injured but Derek was forced to hand over his watch.

"It was a 60th birthday gift and my kids clubbed together to get me something special," Derek told the Wimbledon Guardian.

"After the attack, I would look at my empty wrist for the time and get flashbacks."

James Lamb, Cooper's father, decided to contact the watchmakers (Christopher Ward) directly after seeing the pain on his father-in-law's face.

"Cooper still talks about the bad men with 'a hook'," James said.

"Perhaps he has watched too much Moana as he doesn't know the word knife yet, but he is ok, so is Derek, and that is the main thing.

"The very next day, we all went to Longleat Safari Park to try and forget about it and Derek kept looking at his wrist for the time, bringing flashbacks."

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Much to the surprise and delight of Derek, Christopher Ward got back in touch with them to offer a replacement.

"It was a for a special birthday and this will help build new memories after what happened," Derek said.

"The family were all overwhelmed by the heart-warming generosity of Chris, and it's amazing to have it, I feel so chuffed.

"Massive thank you to them and everyone that was on the common that day that helped out straight after the attack."

Since Derek's ordeal, there have been a few other attacks carried out by moped riders, which police now believe are linked.

There have been no arrests made and enquiries are continuing.

Anyone with information is asked to call 101.