They won 1-0 against fellow top five side AFC Dunstable and the Crows then discovered that second-placed Farnborough and third-placed Barton Rovers had both dropped points.
Spyros Mentis scored the all-important goal for Royston at Garden Walk against a now fifth-placed AFC Dunstable.
Farnborough suffered a 3-0 Cherrywood Road defeat to a now fourth-placed Marlow.
Jordan Brown after 25 minutes and then Chris Ovenden on 75 minutes, after his initial penalty had been saved, and Chid Omokwai three minutes into stoppage time, were the Marlow marksmen.
Barton shared a 1-1 draw at the New Eyrie against top five outsiders Bedford Town, whose Lee Roache popped up with an 88th minute equaliser after Rovers had led through Michael Malcolm`s 10th minute opener.
Sixth-placed Kempston Rovers moved to within two points of the top five after winning 2-0 at Thame against Aylesbury United, Ashley Fuller after 16 minutes and Luke Heneghan 18 minutes from time the Walnut Boys` scorers.
A further three points back are Potters Bar Town, who saw off second-bottom Histon 2-0 at home, courtesy of a second half Eoin Casey brace in the 55th and 72nd minutes.
Hanwell Town just about maintained their outside hopes of a top five spot after winning 3-0 at home against Arlesey Town, thanks to a Will Healey double on 13 and 52 minutes and a third from Kyle Watson eight minutes from time.
Bottom side Petersfield Town are 20 points behind the safety-mark after losing 1-0 at Ashford Town (Middx), whose Mark Bitmead scored the only goal a minute before half-time.
Aylesbury FC pulled themselves six points clear of the bottom two after a comprehensive 4-1 win at Holloways Park against Beaconsfield SYCOB.
Charlie Losasso gave the home side a 37th minute lead but second half goals from Aston Goss, a Brian Haule brace and Ty Deacon deep into stoppage time, wrapped up a terrific win, only spoiled by Haule`s dismissal after his 89th minute second.
Alex Paine`s ninth minute effort eventually proved enough to earn Chalfont St Peter the points at Northwood, while Brendan Matthew bagged a brace for Egham Town in the seventh and 83rd minutes to seal a 2-0 win over Fleet Town at the Runnymede Stadium.
And Mark Janes topped and tailed Kidlington`s 4-2 home win over Uxbridge, whose Danny Bailey and Matty Woods from the spot were on target – Lewis Coyle and Eric Odhiambo sandwiching Janes` brace.
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