IT was Brentwood ladies who claimed bragging rights over their neighbours after this fine win at New Lodge on Sunday.
It was Nikita Whinnett's 14-minute hat-trick that provided the platform for this fully deserved Brentwood victory.
The success, completed thanks to Cristina Fragnito's inaugural goal for the club, means that Brentwood take their place in the draw for the First Round Proper of the premier female knockout competition in the country for the very first time, as well as pocketing £225 in prize money.
Brentwood centre-back Nicole Manning characterised this within two minutes of the start, throwing herself into a crunching tackle on Billericay forward Sophie Whiting to concede a corner.
After both players had received treatment, Nikki Dunsdon was unfortunate to see her header connect with the outside of the right-hand post from Steph Poleyket's flag-kick.
Danielle Kite quickly responded for the visitors, collecting possession from Whinnett and arrowing a driven shot into the gloves of Michelle Bridgeman, who gathered the ball at the second attempt.
Layla Prior rose well to push out Dunsdon's cross above the head of Emma Roberts just before the quarter-of-an-hour mark, and a further opportunity was wasted by the hosts when Dunsdon whacked the ball wide from Whiting's pass.
Brentwood struggled to keep hold of the ball and, when they did launch an attack, they suffered from a lack of bodies in the penalty area in support.
A Billericay counter-attack after Kite had failed to control Whinnett's pass almost led to a goal two minutes later, but Roberts slashed wide from Poleyket's square pass.
There was no profligacy on the half-hour when the favour was returned; Roberts crossed from the right, Whiting helped the ball on and former Brentwood player Poleyket guided her shot beyond Prior to give Billericay the lead.
Having fallen behind, Brentwood were stung into action and an equaliser came within four minutes. Rachel Armstrong and Lucy Faraday were involved in working the ball into the penalty area from the right-hand side and, when it ran loose, Whinnett swooped in anticipation to hoist over Bridgeman and into the top left-hand corner of the net.
Whinnett then latched onto Walker's 60-yard pass to fire underneath the keeper and make it 2-1.
Bilericay Town manager Ian Bent then removed Manning, still struggling with the injury picked up in the opening exchanges, and freshened up the Brentwood side again by bringing forward Fragnito on for Kerri Thomas at half-time.
In the 48th minute Whinnett completed her hat-trick at the end of an exciting move firing her effort into the roof of the net.
Billericay were right back in the game at 3-2 in the 57th minute. Whiting delivered a corner from the right and, although Poleyket's stabbed attempt was blocked, Laura Wheeler rifled the rebound into the net.
Another corner, this time from Poleyket, saw Billericay go perilously close to a leveller as Marie Barker glanced a header inches wide of the left post on the hour and Whiting followed that by skewing wide from Roberts' pass from the resultant goal-kick.
There was some relief when Brentwood restored their two-goal cushion in the 63rd minute.
Like Billericay's second, the goal came from a set-piece as Rose's corner was cleared at the near post. Kite picked up the loose ball and found Fragnito, who forced her effort beyond Bridgeman from close-range to register her first goal for the club.
Brentwood's back-line stood firm to ensure a historic victory.
