Royal enthusiasts sit outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, England, April 27, 2015. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

Police officers chat to royal enthusiasts outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, England, April 27, 2015. REUTERS/Cathal McNaughton 

Britain's Prince Charles and Camilla, Duchess of Cornwall look-alikes, Guy Ingle (L) and Wendy Crawley (R) pose with Royal enthusiast Terry Hutt outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in London, Britain April 29, 2015 REUTERS/Suzanne Plunkett 

A woman walks past decorations left by royal enthusiasts outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, England, April 27, 2015. REUTERS/Cathal McNaughton 

Fans of the Royal family wait outside the Lindo Wing of St Mary's hospital in London, April 20, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

A fan of the royal family wears a union jack hat decorated with badges outside the Lindo Wing of St Mary's hospital in London, April 16, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY 

Fans of the Royal family wait outside the Lindo Wing of St Mary's hospital in London, April 21, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

A fan of the royal family wears a union flag themed blazer outside the Lindo Wing of St Mary's hospital in London, April 16, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY 

Royal enthusiast Terry Hutt tidies up wet decorations posted outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, April 29, 2015. REUTERS/Suzanne Plunkett 

A woman poses next to a betting board showing the odds of baby names outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in London, Britain April 29, 2015. REUTERS/Suzanne Plunkett 

Police officers chat to a royal enthusiast who is camping outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, England, April 27, 2015. REUTERS/Cathal McNaughton 

Royal enthusiasts sit outside the Lindo wing of St Mary's Hospital where Britain's Catherine, Duchess of Cambridge, is expected to give birth to her second child in the next few days, in central London, England, April 27, 2015. REUTERS/Cathal McNaughton TPX IMAGES OF THE DAY 

Fans of the royal family wear union flags outside the Lindo Wing of St Mary's hospital in London, April 17, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks.REUTERS/Neil Hall 

Workers set up barriers for the media pen opposite the entrance to the Lindo Wing of St Mary's hospital in London, April 16, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Peter Nicholls TPX IMAGES OF THE DAY 

A sign indicates the drop off area outside the Lindo Wing of St Mary's hospital in London, April 20, 2015. Britain's Catherine, Duchess of Cambridge, is due to give birth to her second child at the hospital some time in the next two weeks. REUTERS/Cathal McNaughton