A double from on-loan Bournemouth striker Sam Surridge put the home side in front, with his first coming midway through the first half with a header just minutes after Shamir Mullings had hit the woodwork.
In the first minute of injury time Surridge then skipped past Matt Young to put the gloss on a well worked team goal to find the bottom corner and send the home side into the break 2-0 up.
Chelmsford looked a different side in the second half and created good chances for Mullings and the debuting Elliot Buchanan, but any chance of City getting a point from Dorset was ended when Marvin Brooks found the top corner with a tremendous strike.
The third goal knocked the stuffing out of the visitors and the Dolphins came close to grabbing a fourth almost immediately with Surridge rounding Fitzsimons but couldn’t get his shot away.
Surridge then completed a perfect hat-trick having scored with his left foot and head in the first half, as Phil Walsh gave away a penalty with Fitzsimons going the wrong way as Surridge’s right footed spot kick nestled in the bottom corner.
Chelmsford’s 11-game unbeaten run in the league came to an unceremonious end with the Clarets dropping down to third after Ebbsfleet went second.
It was an afternoon to forget for the Clarets following dropped points in their previous two league games against Hemel Hempstead and Concord Rangers. The big team news going into the game with Poole was that new signing Elliot Buchanan went straight into the starting line up for his Clarets debut.
Buchanan was the league top goal-scorer last campaign under Rod Stringer at Bishop's Stortford and signed on Thursday night from Margate, and was placed on the left of a three-man attack with Shamir Mullings and Shaun Jeffers.
Top goal-scorer Mullings came straight back into the starting line up having missed the draw with Concord through suspension looking to add to his 13 goals in all competitions and he came within millimetres of adding to that haul with the game’s first clear chance when Daniel Blanchett’s low cross fell to Mullings who smashed the post.
There hadn’t been many chances to report on, on a crisp November afternoon down in Dorset, but midway through the half Chelmsford fell behind when Sam Surridge headed in from close range.
Luke Burbidge went one-on-one with Adam Bailey-Dennis and picked out a cross that landed perfectly onto the head of Surridge, whose header had enough power to beat Ross Fitzsimons.
Bailey-Dennis had looked like he’d been struggling and was immediately replaced by Phil Walsh after the goal and the home side kept the pressure cranked up on the visitors as City were struggled to get a foothold in the game.
Right on the half time interval the home side made their pressure count as they scored in the first of four added minutes at the end of the first half through Surridge once again.
A sweeping move forward by Poole saw Luke Burbidge and Surridge link well leaving the Poole forward one-on-one with Matt Young who Surridge skipped past with ease before finding the bottom corner to grab his and Poole’s second of the game.
Chelmsford had come back from 2-0 down and 3-0 down previously in matches this season and the would have to do it against if they were to get anything on the South Coast as they went in at the break deservedly 2-0 down.
Rod Stringer would have been looking for an early goal from his side in the second half to get them back into the game and Buchanan came close to getting a debut goal, just failing to get his head on the ball from close range after being found by a Mullings cross.
Mullings had a low strike fumbled by Nick Hutchings in the Poole goal with his defenders helping him out with the clearance. Mullings then had a good chance with his head when he was unmarked at the Clarets corner but failed to get a good connection.
Chelmsford were looking a different side in the second half and created a half chance for Max Porter who struck just wide after being found by a Willmott cross, but City were left deflated as out of nothing Poole went further in front through Marvin Brooks.
From the edge of the area Brooks sent the ball flying into the top corner to all but put the game to bed with Chelmsford needing a Hemel Hempstead-esque comeback to salvage anything from this game and maintain their unbeaten league record.
Any hope of that coming to fruition was ended quickly though when Surridge completed his hat-trick from the penalty spot after Walsh had brought the forward down in area.
Having scored with his head and his left foot in the first half, Surridge sent Fitzsimons the wrong way with his spot-kick with his right foot, completing a perfect hat-trick and securing the three points for the Dolphins.
The fourth for Poole was the tenth goal the Clarets had conceded in their last three league games as City’s defensive woes continued and it brought about Chelmsford’s first defeat since August when they lost to league leaders Maidenhead United.
Billy Bricknell was brought on late and came close to grabbing a consolation deep in the second half when he ran clear, but after cutting back onto his right foot two Poole defenders got back to stop the shot to round off a miserable afternoon for City.
1. Nick Hutchings
2. Lewis Lindsay
3. Ryan Case
4. Michael Walker
5. Jamie Whisken (C)
6. Carl Pettefer
7. Luke Burbidge
8. Steve Devlin
9. Sam Surridge
10. Marvin Brooks
11. Luke Roberts
12. Corby Moore (On for Carl Pettefer 68’)
14. Tom Rees
15. Abdulai Baggie (On for Marvin Brooks 67’)
16. Richard Gillespie
1. Ross Fitzsimons
2. Matt Young
3. Daniel Blanchett
4. Max Porter
5. Adam Bailey-Dennis
6. Mark Haines
7. Robbie Willmott
8. Anthony Church (C)
9. Shaun Jeffers
10. Shamir Mullings
11. Elliot Buchanan
12. Billy Bricknell (On for Shaun Jeffers 78’)
14. Phil Walsh (On for Adam Bailey-Dennis 30’)
15. Josh Rees (On for Elliot Buchanan 60’)
16. Max Cornhill
18. Luke Daley
Poole Town: Sam Surridge 26’, 45+1’, (p)66’, Marvin Brooks 56’
Chelmsford City: None
Poole Town: None
Chelmsford City: Mark Haines 44’, Daniel Blanchett 45+4’, Anthony Church 90+1'
Referee: Andrew Laver
Assistant Referees: Tom Holden & Daniel Flynn
City Man of the Match: Shamir Mullings