Steve Howard's second half goal won Luton three points from a scrappy game at Kenilworth Road. The Blues rarely tested Hatters keeper Marlon Beresford but might have had a first half penalty for a foul on Jimmy Juan.
Loanee Juan returned, with Ian Westlake, out for the season with an ankle problem, and Jim Magilton also missing. Richard Naylor went up front with Alan Lee, while Jay McEveley, a player Joe Royle is keen to sign permanently in the summer, replaced Scott Barron at left-back.
The game started scrappily, the first incident of note a late tackle on Sito by Howard who probably only escaped a yellow card as it was so early on in the game.
A supporter wearing a Watford shirt in the sold-out Town section attracted the attention of the home fans and then the stewards and the police, an incident which provided more entertainment than the players as the first 20 minutes passed without a shot on goal.
When the first effort of the game came, on 21, Beresford uncomfortably bundled Darren Currie's 25-yard shot over the bar, the midfielder having been teed-up by Richard Naylor, the Blues having enjoyed the better of the possession.
With Jimmy Juan briefly off the pitch having treatment for a head injury, Shane Supple did well to rush from his line and claim the ball at the feet of Kevin Foley.
The Town keeper made an even better save soon after, coming out to block in front of Steve Robinson after Jason De Vos had missed a header. The Irish stopper made a third save within a couple of minutes, diving to his left to save from Rowan Vine but the Luton striker had strayed offside.
Supple saved Howard's 25-yard shot with little trouble, before the Blues had their best chance of the game and might have had a penalty. Jimmy Juan was set in on goal by Alan Lee's header and appeared to have his foot taken from under him by Markus Heikkinen as he hit his shot. However, referee Lee Mason, who sent Sito off in the East Anglian derby at Portman Road earlier in the season, gave a corner, much to the frustration of the Town players.
From the corner, Matt Richards's shot was blocked as Town continued to look marginally the better side, without passing the ball around with the fluency they have shown in recent weeks.
Just before the break, the home side had two chances, Heikkinen shooting over from 25 yards and Robinson hitting the sidenetting from a tight angle on the right.
Not a first half which too many will recall too fondly, good football was rare, although both sides could have had goals with Shane Supple putting in another excellent display.
The Hatters had tried to disrupt Town's natural game by closing players down quickly, while getting the ball forward quickly when they were in possession.
The Blues started the second half brightly, Owen Garvan almost playing in Alan Lee. At the other end, Dean Morgan cut in from the left but sent his shot well over the bar.
Jay McEveley almost gifted Howard a goal in the 52nd minute, heading the ball weakly towards Shane Supple from distant and putting the Luton striker through one-on-one with the Town keeper. Fortunately for the Blues, Howard shot into the sidenetting, McEveley subsequently indicating that he felt Supple was slow to come off his line.
Supple, Town's best player on the day, made another fine save in the 54th minute, getting down to his left to save Carlos Edwards's shot. Soon after, Dean Bowditch replaced Matt Richards on the right of midfield.
Just before the hour, Jimmy Juan shot wide from 25 yards, then Lee struck a weak effort to Beresford with Bowditch screaming at him from a much better unmarked position to his right.
For Luton, Chris Coyne headed Morgan's corner wide through a crowd of players, prior to Howard picking up a yellow card for a foul on Sito. Sol Davis got his name in the book only moments later for an off the ball attack on Bowditch right in front of the referee which some officials might have considered a more serious offence.
On 65 Jimmy Juan hit a freekick into the wall from 20 yards, just before Heikkinen received a caution for a foul on Lee.
Sito superbly blocked Carlos Edwards's shot from the right as Luton broke quickly. From the corner, Jason De Vos's clearance cannoned off the Spaniard on the edge of the six-yard box and, very luckily, into the arms of Supple.
Lee beat Coyne on the Town right but sent his shot wide, the Blues failing to create themselves clear-cut chances.
Richard Naylor carved out a rare good shooting chance for Owen Garvan breaking through from midfield on 75 but the Irish youngster's shot was blocked. Garvan went wide a minute later after the ball had broken to him following some head tennis inside the area.
The only goal of the game came in the 80th minute. Sito failed to clear the ball from a position wide on the Town right from where Ahmet Brkovic crossed to the near post, Howard flicking a header to Supple's right and into the net.
Brkovic, only on as a sub four minutes before creating the goal, received a yellow card for an off the ball push on Fabian Wilnis, referee Mason having consulted with his linesman before issuing the caution.
Howard should have added to his side's lead in the 85th minute but sent his header over the bar from a matter of feet while completely unmarked. Town introduced Danny Haynes for Sito as they switched to both a three-man attack and three-man defence. As time ran out, Vine shot over, then Naylor headed wide.
A disappointing typical end of the season game, scrappy from start to finish with the Blues enjoying the better of the possession while rarely showing too much quality or penetration up front, illustrating why Joe Royle is so keen to sign Ricardo Fuller over the summer.
Luton's more direct approach saw them have the better chances, but another fine performance from Shane Supple and some poor finishing prevented them from scoring more goals.
Town's best opportunity was the first half chance which fell to Juan which could well have been a penalty.
The Blues won a lot of corners and freekicks around the penalty area throughout but, as so often in recent weeks, Darren Currie's balls into the box lacked precision.
Jay McEveley, back after his lengthy injury absence, generally showed strong defensive capabilities but, as earlier in the season, was often let down by his distribution.
Town: Supple, Sito (Haynes 85), McEveley, Wilnis, De Vos, Garvan, Juan, Richards (Bowditch 54), Currie, Lee, Naylor. Unused: Price, Skard, Casement. Att: 9,820.