Prior to this round 16 setback Andrew Leering’s side had climbed to second position in Birmingham Premier League Division One on the back of a string of consistent displays.
However, with five of their top six reaching 25 and none going beyond Harrison’s 57 Wardens were very much the architects of their own downfall on a day when their ultra-aggressive approach to playing spin failed to pay off.
This approach saw the hosts subside from 185 for three to 242 all out with 14 balls of their 55-over allocation unused while Peter Clark finished with the fine figures of 6-58.
And Shrewsbury went on to take full advantage of chasing a target which must have been 50 fewer than anticipated thanks to a Rhodri Evans half-century plus an unbroken 81-run sixth-wicket partnership between Rob Foster and Tyler Ibbotson which saw them home in the 48th over.
Although Barnt Green claimed a big win, with title rivals Smethwick and Moseley also suffering defeats Wardens now lie in fourth place in the table as the competition reverts to its win/lose white ball format for the closing six rounds of action.
“Too many of our batters got in and then got out playing too aggressively,” Leering acknowledged.
“We went much too hard at their spinner who ended up with six wickets and having picked an extra bowler we needed one of the top order to do what they have in recent weeks and make a big score.
“As a result we were probably 30 short of being competitive and we then made things worse by not bowling consistently enough - there were too many bad balls which went for four.
“Had we picked up another couple of wickets when we had them five down it might have been interesting as they had a very youthful tail, but it wasn’t to be.”
Harrison and opening partner Henry Cullen took full advantage of being offered first use of a good Glasshouse Park pitch to race to 77 before the Worcestershire wicket-keeper was bowled by George Garrett for a 34-ball 42 containing eight boundaries.
Ali Zaryab (17) then helped Harrison - whose 64-ball 57 contained a six and nine fours - add 55 for the home side’s second wicket before both fell in quick succession.
Harry Johnson (33) and Reeve Evitts (36) then put together the home side’s third half-century stand before both fell to Clark.
But once Leering was run out for 26, a Wardens line-up containing five specialist seam bowlers plus off-spinner Neylan Chauhan saw its lower-order blown away to such dramatic effect that the last six wickets added just 29 runs in the face of accurate spells from Clark and Evans (2-55).
Tommy Rex immediately dented Shrewsbury’s confidence by trapping skipper Will Parton lbw with the sixth ball of the response but thereafter the visitors built a series of useful partnerships which chipped away at their 242-run target.
Opener George Hargrave (30) helped Evans add 58 for the second wicket before Llyr Thomas made 33 from 36 balls while building a useful 56-run alliance with Evans for the visitors’ third wicket.
When wicket-keeper Matthew Swift’s dismissal was soon followed by the end of Evans’ stay – which delivered a 92-ball 63 containing ten fours – the hosts sensed opportunity.
However, the experienced Foster had other ideas, and in the company of Ibbotson he set about taking the visitors away from the relegation zone by building a 91-run sixth-wicket partnership which sealed their fifth success of the season.
Foster finished with an unbeaten 53-ball 45 while his partner contributed a breezy even-time unbeaten 37. Reeve Evitts took 2-71 for Wardens for whom the unlucky Alex Wyatt was the pick of the attack.