Hi Mark. As Phil said, if it had a black hood it could only have been either a 2nd summer, 3rd summer or adult summer. Their distinctive shape and impression that Laurie talks about really is obvious once you get to know them, they are generally a larger bird, with more chunky proportions, larger bill, head, wings etc. The legs are also longer which makes the bird stand out from a standing flock.
Juvenile's are much browner and show a very neat (and somewhat attractive' scaly pattern on the upperwings.
1st winter/summer is always the hardest to ID, with varying hood markings in each individual, the 'scaps' are moulted off so only the juv type coverts are left, making it look fairly similar to a BHG.
2nd winter summer pretty much resembles an adult, apart from the alternating black and white pattern on the primarys.
Adult Meds and very distinctive, with pearly grey upperparts, silky grey underparts and wingtips and the jet black hood constrasting to the large 'clown eyelids' and blood red bill
Photo's should show 2 juv's, a 1st summer, a 2nd summer and 2 adults and a 1st summer.
Happy gulling :t:
MB