The New Zealand rider was last into the arena before this morning’s coffee break and he produced a mistake-free test to earn a score of 38.8.
Jock was disqualified after the competition last year when Clifton Promise tested positive for the banned substance reserpine. However Jock was cleared of any wrongdoing by an FEI tribunal last month.
Jock came straight to the Burghley Horse Trials from last weekend’s World Equestrian Games in Normandy, where he pulled up on the cross-country.
Tomorrow sees the competitors take on the famous Burghley cross country course ahead of a day of show jumping on Sunday.
Eight appliances at scene of Cransley fire
Kettering town centre restaurant ready to reopen with new menu and 'surprises'
Remembering the drought of 1976 across Northamptonshire in pictures from the archive
Wellingborough military veteran John Ruddock had cache of hundreds of indecent pictures and videos
All the pictures from Florence Bark's football fundraiser in Oundle
Burghley Horse Trial Day Two Standings - Top 10
1 CLIFTON PROMISE - Jonathan Paget - 38.8
2 BAY MY HERO - William Fox-Pitt - 39.5
3 HAPPY TIMES - Sam Griffiths - 40.2
4 AVEBURY - Andrew Nicholson - 40.5
5 RUTHERGLEN - Andrew Hoy - 40.8
6 ARTHUR - Allison Springer - 41.2
7 VAGUELY NORTH - Aoife Clark - 44.7
8 WESTWOOD MARINER - Piggy French - 45.8
9 LAMICELL UNIQUE - Karin Donckers -46.3
10 RF DEMETER - Marilyn Little - 47.5