The bigger ones usually hit the shores around may/june time and then head off to wrecks and deep water for a while. It is then common for them to make another appearance inshore around around now for a while before they scoot off on their winter holidays - as you have just experienced. The smaller specimens will be around all summer though till around October time.
They are back on the Kingmere reef just offshore of Littlehampton at the moment too, I'm out in the boat to nab a few on Monday before they disappear. Enjoy it while it lasts!