Ben Sanderson followed early in the afternoon session, caught at second slip off an outside edge with Northamptonshire still in arrears, but that quickly changed as Guthrie launched a fiery salvo against the seamers.
The left-hander patted his first ball from Sharma over the wicketkeeper’s head for four and maintained the offensive, pulling and hooking a string of boundaries before clubbing Toby Roland-Jones for six.
Another top-edged four off Helm took Guthrie to a 45-ball half-century and, once he finally fell to a sharp one-handed catch by Robson at second slip, the home side were within sight of a fourth batting bonus point.
Sales, having cracked Luke Hollman for two sixes to pass 150 for the first time, duly notched up that collective target with a boundary off Roland-Jones before holing out to long-off on the stroke of tea.
There were a couple of early alarms for Middlesex’s openers when they began their second innings, with De Caires almost playing on and Robson’s edge off Harry Conway shelled at slip by Ricardo Vasconcelos.
But they did enough to see off Conway and Sanderson and it was home captain Luke Procter who achieved the breakthrough, winning an lbw decision against De Caires with Middlesex only halfway to wiping out the deficit.
Robson settled into the groove, though, cutting with authority and steering Guthrie to the mid-wicket fence to take his side out of the red, while Holden unveiled some classy strokes to negate the leg-spin of Calvin Harrison.
