Gillingham had a day to forget in East London.

The Gills conceded four in the opening half as a brace from David Mooney and goals for Dean Cox and Kevin Lisbie put the outcome beyond doubt.

Orient added a fifth late on through substitute Chris Dagnall before Craig Fagan gave the big away following at least something to cheer with a consolation.

Defeat at Orient was Gillingham’s third in a row in League 1 and leaves them five points off the relegation places with four games remaining.

There was a change in central defence for the Gills as injuries meant boss Peter Taylor was forced into a reshuffle.

Leon Legge remained out with a hamstring injury and that meant a place in the heart of Gills’ defence for Charlie Lee.

There was no place in the squad for Bradley Dack but Chris Whelpdale did make a reappearance, on the bench. The midfielder had missed the previous eight games.

Orient topped the League 1 table in the opening months of the season but started Saturday’s game 13 points adrift of the leaders and aiming to motivate themselves ahead of an expected play-off campaign.

The Gills needed another win to finally banish fears of being dragged into the scrap at the other end of the table.

Saturday’s game was over before it had barely started for the Gills, as their defence was sliced open twice in the opening eight minutes.

Four minutes had gone when Orient had their first. The Gills were caught asleep at the back, John Lundstram played the ball through an open door and David Mooney finished past Stuart Nelson.

Dean Cox fired home the second goal with eight minutes gone. Orient had knocked the ball around inside the box before Mooney laid the ball off to Cox and he finished well.

The Gills remained second best but had a couple of half chance. Amine Linganzi’s weak effort was saved by keeper Jamie Jones, while Elliott Hewitt and Adam Barrett headed over.

Former Gills loanee Kevin Lisbie got the third goal in the 34 minute, with a powerful header, after being picked out by Moses Odubajo.

The home crowd had barely finished celebrating the third goal when the Gills were caught out again, in simple fashion. Dean Cox found Mooney and he tucked away the fourth.

The visiting crowd – numbering over 1,000 – made their feelings known with chants of “we want our money back”.

Gills boss Taylor sent the same XI out for the second half and they made a positive start. A deflected effort by Linganzi bounced just wide.

The visitors saw a lot more of the ball in the second half but by then the damage was already done.

Gillingham were playing a dangerous game as they committed extra men forward and with 12 minutes left the hosts made them pay. Dagnall evaded the attention of Jake Hessenthaler and as Barrett backed off, he pulled the trigger, finding the bottom corner.

The Gills pulled one back with eight minutes left, as Fagan crashed home a shot but it was too little too late.

Gillingham: Nelson, Martin, Harriman (Smith 67mins), Lee, Barrett, Linganzi, Hewitt, Fagan, Hessenthaler (Gregory 89mins), McDonald, Weston (Birchall 63mins). Subs not used: Baxter, Whelpdale, Akinfenwa, Borrowdale.

Leyton Orient: Jones, Omozusi, Vincelot (Ness 70mins), Cuthbert, Baudry, Cox, Lisbie (Batt 79mins), Mooney (Dagnall 70mins), Odubajo, Clarke, Lundstram. Subs not used: Sawyer, James, Larkins, Simpson.

Attendance: 5,128 (1,154 away)