Carl Mills has been jailed for life for each of the three counts of murder and must serve a minimum of 30 years before he will be considered for parole.
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Gary Martin and his son Dale had plotted to throw drugs over the prison wall hidden in plastic egg-shaped containers.
Visitors to the centre can get a close-up look of the birds, which have been breeding in the area since 2004.
A public inquiry into undercover policing in England and Wales is to be formally opened today.