Police praised her for slowing the robbers down — but she didn't feel like a hero when it happened.
"I texted my daughters to tell them that their mum was a numpty. I labelled myself a numpty when I realised what I had done."
But her grandchildren, Thomas, 11, and Katie, nine, prefer to call her "supergran".
"They keep telling me I am supergran — they are very proud of me."
After the raid, Sandra matter-of-factly began tidying up the mess the robbers had left behind.
But as she walked home, the enormity of what she had done suddenly hit her.
"I was walking home on my own. It hit me, what I had done. I was crying and in shock."
Asked if she would do the same thing again, she said. "I don't know. It's just a reaction." She added: "I always try to do what's right."
Last month William Cochrane, 39, his brother Richard Cochrane, 37, and Scott Lister, 30, were jailed for a total of 21 years and three months for the June 2016 robbery.