United were unlucky not to get a goal back when keeper King made a hash of collecting Phil Mason's cross. King held it, then stepped backwards and the ball appeared to go over the line but the assistant referee shook his head. United's only other chance in the half was on 29 minutes, Steve Heard passing to Darren Grieves who was fouled by King.
On 34 minutes United's defence went AWOL as Baker centred from the by-line and Gentle struck his second goal from close range. Less than a minute later Baker slotted in the fourth with United still shell-shocked.
Eleven minutes into the second half Baker raced clear, cut inside and shot. Phillips managed to parry but only into the path of Browne who finished off with ease. Billericay went close three more times, whilst Bobby Highton shot well over, and near the end a Mason free kick came back off the bar. But the damage had already been done in a terrible first half for the visitors.