The jury at Lewis Crown court heard how Lauren Bishop, Michael Clark and Edward Phillips, met up after and celebrated by buying and drinking alcohol on the seafront.
CCTV from the Londis store nearby showed Phillips and Clarke laughing and joking shortly after carrying what the court heard was a brutal, vicious and horrific attack.
More top news
Tuesday morning's weather for the west of the region
Tuesday morning's weather for the east of the region
Monday evening's weather for the east of the region