Terry Spence, chairman of officers' representative body the Police Federation, said the device was planted by "cowardly thugs":
This was an attempt to murder an off-duty police officer.
But this attack is no great surprise. Scores of police officers have been forced from their homes in the last 12 months because of terrorist incidents. This is just the latest of many.
It reinforces the need for officers to be extra vigilant.
More top news
The royal told GQ Magazine: "I would love her to have met Catherine and to have seen the children grow up."
Police said they were called to an incident at Hamerton Zoo in Cambridgeshire but gave no further details apart from no animals escaped.
A man's body has been discovered in the sea off the Kent coast.