birmingham nec

i attended the birmingham concert at the nec on nov 9th,it cost £8 to park,i am a big fan of smokie and they came on first,unfortunatly thats when people started coming in and blocking my view,they had drinks so they had timeto go to the bar first.it spoilt my night,then when david cassidy came on he was swaying and appeared drunk and was wearing rediculously tight trousers,i couldnt understant what he was singing,at the end he suddenly left before finishing his song,he also kept complaining his flight was delayed and he was late which common sense would have told you to come the day before.the concert was dissapointing.why do people arrive when the concert had already started just because they didnt want to see the first act others do.