Zoo keeper Jo Shirley from ZSL Whipsnade Zoo, Dunstable, Bedfordshire, with an orphaned baby wallaby that is being hand-reared by keepers. Picture date: Monday April 30, 2012. The orphaned baby wallaby is busy settling into her new home - which comes in the shape of a rucksack. Tiny Tilly is being hand-reared by keepers at ZSL Whipsnade Zoo after she was found out of her mum's pouch a month ago. She is being looked after by keeper Jo Shirley who carries her around in a substitute pouch made from a rucksack wherever she goes - just as her real mum would do. Photo credit should read: Steve Parsons/PA Wire

London Mayoral candidate Ken Livingstone at the launch in south London of a poster supporting his campaign to be Mayor of London today. Picture date: Monday April 30 2012. The London mayoral election takes place on May 3. See PA story POLITICS Mayor. Photo credit should read: Stefan Rousseau/PA Wire

A seagull lands on a man's head at Circular Quay in Sydney, Australia, Tuesday, May 1, 2012.(AP Photo/Rob Griffith)

Jeon Sang-Guen of South Korea competes in the Men's +105kg during day seven of the Asian Weighlifting Championships at Yichung Culture & Sports Center on April 30, 2012 in Pyeongtaek, South Korea. (Photo by Chung Sung-Jun/Getty Images)

Manchester City manager Roberto Mancini and Manchester United manager Sir Alex Ferguson (left) argue on the touchline.

Women dressed as witches dance during the Walpurgis Night at the famous Hexentanzplatz (Witches' dance ground)' in the Harz mountains near Thale, northern Germany, Monday, April 30, 2012. Hundreds of costumed devils and witches meet to celebrate Walpurgis Night, a traditional religious holiday of pre-Christian origins. (AP Photo/Jens Meyer)

A torn safety net on One World Trade Center provides a window view of the Manhattan skyline, Monday, April 30, 2012 in New York. One World Trade Center is being built to replace the twin towers destroyed in the Sept. 11 attacks. It reached just over 1,250 feet on Monday. That's just taller than the observation deck on the Empire State Building. (AP Photo/Mark Lennihan, Pool)

Palestinian protester, wearing a national flag mask, takes cover during clashes with Israeli troops outside Ofer military prison near the West Bank city of Ramallah on May 1, 2012, following a demonstration in support for prisoners held in Israeli jails. Clashes erupted between stone-throwing youths and the Israeli army, who fired tear gas, rubber bullets and a foul-smelling liquid known as 'skunk' to break up the demonstration. AFP PHOTO/ABBAS MOMANI (Photo credit should read ABBAS MOMANI/AFP/GettyImages)

Militants and labour union members gather around a burning the effigy of Philippine President Benigno Aquino in Manila on May 1, 2012 as part of the May Day protests demanding higher wages and policies that would make it harder to fire workers. Aquino has said he is trying to help labour but has warned that giving too many benefits will make the country less competitive, costing more jobs. AFP PHOTO/NOEL CELIS (Photo credit should read NOEL CELIS/AFP/GettyImages)

Swan glide through the flooded riverside walkways in the shadow of the cathedral in Worcester. (PA)