Gemma's father Anthony McCluskie said today:
"This has been an extremely traumatic year for myself and my wife Carole, my son Danny and his partner Shantelle, Gemma's extended family and all her many friends.....To some of her friends Gem was known as 'Gemstar' or 'Li'l Gem', small in stature, she was huge in personality with a zest for life.
"Gemma was a daughter, a sister, an aunty, a cousin and a niece and is very much loved and greatly missed."
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The plaque at number 16 Cowley Street in Westminster marks the brown brick Georgian townhouse where Sir John lived for 31 years.
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Metropolitan Police officer, Tom Harrison, has been crawling the course since the race began on Sunday morning.