March has not been the month London Irish had hoped it would be: a winning run came shuddering to a halt in the Guinness Premiership with a sequence of defeats by Gloucester, London Wasps and Bath, but the sun shone on the Madejski Stadium yesterday and the Irish put their domestic house in order just in time for their European commitments.

The victory over Bristol, whose minds are now, by their own admission, on next season, was not a thing of beauty but it lifted the spirits for the Heineken Cup quarter-final against Perpignan on Sunday. As the Irish know from their two pool games with the French club, that will be no picnic, but if they can make it through to the last four, that will go a long way towards retrieving their season.

Yesterday did not improve their league standing from eighth and they have hard work to do to climb into the top six and qualify for next season's Heineken Cup. But such luminaries as Peter Richards and Shane Geraghty are closing fast on full fitness and, if the two England backs can train all this week, they could yet feature in the match squad against Perpignan.

“We weren't perfect in our execution but it was a very professional job,” Brian Smith, the Irish director of rugby, said. “We knew we needed a solid win to get momentum going. We have to step up by 25 per cent across the board but Bristol are a very lumpy side, as are Perpignan, and today was a good dress rehearsal.”

The West Country club have no such late-season drama to concern them. Several players may be competing for contracts but you would not have thought so, given the paucity of their first-half handling. Tom Arscott collected a try late in the game but he might have scored a couple more had Bristol's backs been able to pass the ball in front of one another and reward the hard work of their forwards.

The collapse of their lineout in the final quarter did not help but the efforts of Ian Grieve, on his full debut, and the fresh legs of an ambitious youngster in the form of Redford Pennycook helped to add a degree of dignity to the scoreboard by the end. Their start, perhaps, reflected the untidiness of their game in that the kick-off went direct into touch and Reading's small in-goal area may have denied Sailosi Tagicakibau a try from the resulting scrum.

It was left to the other wing, Topsy Ojo, to prompt the first of three Irish tries. Peter Hewat, who ended the afternoon with 18 points, exchanged penalty goals with Ed Barnes and when Tagicakibau attacked off a missed Bristol clearance, Ojo was involved three times in the move completed by Stuart Mackie.

The extent of Bristol's troubles was emphasised by the stream of penalties awarded against them by the referee, Dave Pearson, who did not complete the match because of a calf strain.

Joe El Abd, their captain, received a general warning but it was the second half before Pearson flourished a yellow card at Jason Hobson, the tight-head prop, for blatant offside play, Hewat adding penalties either side of the interval.

Before Hobson's return, the Irish scored their second try when Hewat chased a kick ahead by Paul Hodgson. Shaun Perry and Luke Arscott scurried back but the bounce of the ball baffled them and Hewat touched down, giving the Irish the scope to remove from the field Mike Catt, whose experience is so crucial to their European hopes.

Hewat, the Australian full back, was back in the corner to make a try-saving tackle on Tom Arscott straight from the restart and was involved again in Irish's third try. Twice the forwards drove from a close-range lineout before the ball went wide and Hewat's inside pass gave Seilala Mapusua the easiest of tasks to touch down.

Scorers: London Irish: Tries: Mackie (23min), Hewat (55), Mapusua (64). Conversions: Hewat 2. Penalty goals: Hewat 3 (14, 30, 49). Bristol: Try: T Arscott (77). Penalty goal: Barnes (19).

Scoring sequence (London Irish first): 3-0, 3-3, 10-3, 13-3 (half-time), 16-3, 23-3, 28-3, 28-8.

London Irish: P Hewat (rep: W Fury, 68); S Ojo, G Tiesi, S Mapusua, S Tagicakibau; M Catt (rep: E Hickey, 56), P Hodgson; T Lea'aetoa, S Mackie (rep: J Clark, 80), F Rautenbach (rep: D Murphy, 65), N Kennedy (rep: J Hudson, 65), R Casey (rep: G Johnson, 74), D Danaher, S Armitage, P Murphy (rep: J Leguizamon, 68).

Bristol: L Arscott; T Arscott, R Higgitt, N Brew (rep: L Eves, 65), D Lemi; E Barnes (rep: J Strange, 65), S Perry (rep: H Thomas, 65); D Crompton (rep: P Bracken, 59), M Regan (rep: S Linklater, 50), J Hobson (sin-bin, 49-59), N Budgett, S Hohneck (rep: M Sambucetti, 59), I Grieve (rep: Bracken, 50-59; rep: H Pennycook, 65), J El Abd, D Ward-Smith.

Referee: D Pearson (rep: J Dennison, 74).

Attendance: 7,573.