Photo 11: LBBG 3cy, June 16 2001, Missouriweg, Maasvlakte, the Netherlands. 

A huge male, spending much time between breeding adults. Many of the upper parts are adult-like and the bare part coloration is much more in line with older immatures, especially applying 4cy LBBG.

In second summer (3cy) LBBGs, the tail feathers can show distinct differences: it might be anything from a clear tail-band, spaghetti pattern, black-and-white variegate patterns to snow white. Here it is clearly white, not very common in 3cy.

So why is it in 3cy and not older, e.g. 4cy? The primaries are very typical for 3cy, with the outer primaries bleached 2^nd generation, without tips and no mirror on p10.
Nevertheless, it's hard to fully exclude 4cy LBBG, especially with such advanced upper-parts.

Taking the primaries as conclusive for ageing such a bird, it certainly is a 3cy. Best is to wait till it raises its wing and check the inner primaries and secondaries (not seen in this bird).