Harlequins head coach Jason Gilmore described Marcus Smith, who conducted play brilliantly, as the side’s ‘game driver’ Credit : Warren Little/Getty Images Marcus Smith wielded the conductor’s baton as Harlequins produced a breathtaking second-half comeback to stun Exeter Chiefs amid a carnival atmosphere at Allianz Stadium. While the bands played and supporters partied in the stands during the “Big Summer Kick Off”, it was Smith who orchestrated events on the pitch, conducting Harlequins from complete disarray to irresistible dominance with a tactical masterclass. The comeback not only reignited Harlequins’ Champions Cup ambitions, it dealt a blow to Exeter’s own play-off hopes. For much of the first half, Quins looked badly out of tune. The Chiefs, on the other hand, struck the opening notes through Campbell Ridl, who gathered Harvey Skinner’s pinpoint cross-field kick to score in the corner, before Stephen Varney sprinted under the posts following slick work from Paul Brown-Bampoe and Henry Slade.…