But on a day dominated by the bowlers, the home side hit back to reduce their opponents to eight for three in reply before they recovered to close on 175 for six, with skipper Nicky Boje leading the fightback.
Pitch inspector John Jameson deemed t
hat swing, rather than any problems with the pitch, was mainly responsible for 16 wickets falling.
Gloucestershire's Chris Taylor, with 51, and County captain Boje (57 not out) were among few batsmen to make any impression.
Boje invited Gloucestershire to bat after winning the toss in cool, overcast conditions and soon saw the decision pay off.
The pitch had pace in it and opener Kadeer Ali was forced to retire hurt after being struck on the helmet by a rising delivery from paceman Johan van der Wath.
Soon the hosts were 17 for three as Lucas bowled Will Porterfield shouldering arms and gained lbw decisions against Alex Gidman and Hamish Marshall, both playing across the line.
Taylor and James Franklin (24) took the total to 66 before Franklin carelessly clipped Andrew Hall to Lucas at mid-wicket.
Then Steve Snell fell to the same bowler for a second-ball duck.
It was 103 for five at lunch, with Taylor unbeaten on 34.
He went on to a half-century off 74 balls, with nine fours, but then loosely drove at a wide ball from Lucas and edged to wicketkeeper Riki Wessels.
Richard Dawson made 21 and Jon Lewis 13 not out, but the damage had been done.
Kadeer returned only to fall for a duck and Gloucestershire failed to claim a batting point for the third successive game.
Lucas was well supported by van der Wath (three for 47) and Hall (two for 20), with van der Wath cleaning up the tail.
Soon Gloucestershire's bowlers were making the new ball talk as well.
Youngster Ben Howgego continued his difficult introduction to first-class cricket as he was lbw to Steve Kirby in the first over without scoring, and Franklin quickly accounted for the in-form Stephen Peters and out-of-sorts Rob White.
When Wessels was lbw to Lewis aiming to leg it was 39 for four and that became 91 for five after tea as Alex Wakely fell in similar fashion for a battling 30.
Boje needed several moments of good fortune to reach 50 off 89 balls with eight fours.
He was caught in the slips off a no-ball from Franklin on 42 and had a tough time against Kirby straight after tea.
But the Northants skipper also produced some well-timed strokes to ensure his side gained a first-innings lead.
Kirby got his reward for some hostile spells when Hall, on 41, holed out to Lewis at deep square.
But with the County already 28 runs ahead and with four wickets in hand, they can be pleased with their day's work.
LV County Championship
Division Two
Gloucestershire v Northantsat Cheltenham, day one of four
Northants won the toss
Gloucestershire first Innings
Kadeer c Boje b Lucas 0
Porterfield b Lucas 0
H Marshall lbw b Lucas 6
A Gidman lbw b Lucas 8
C Taylor c M Wessels b Lucas 51
Franklin c Lucas b Hall 24
Snell c M Wessels b Hall 0
Dawson c M Wessels b van der Wath 2
J Lewis not out 13
Kirby b van der Wath 0
Ireland c Wakely b van der Wath 2
Extras (14nb 4b 4lb) 22
Total (All out, 42.4overs) 147
Fall: 2, 10, 17, 66, 68, 126, 132, 132, 139, 147
Bowling: van der Wath 14.4 4 47 3, Lucas 15 4 49 5, Hall 5 1 20 2, Wigley 5 1 16 0, Boje 1 0 2 0, Panesar 2 0 5 0
Northants first innings
Peters c Sub b Franklin 1
Howgego lbw b Kirby 0
R White lbw b Franklin 0
Wakely lbw b J Lewis 30
M Wessels lbw b J Lewis 23
Boje not out 57
Hall c J Lewis b Kirby 41
van der Wath not out 6
Extras (7nb 1w 4b 5lb) 17
Total (for 6 wkts, 51 overs) 175
Fall: 1, 1, 8, 39, 91, 162
Bowling: Kirby 13 2 52 2, Franklin 12 2 39 2, J Lewis 9 1 37 2, Ireland 9 3 24 0, Dawson 8 3 14 0
