Joe Root's 16th Test century highlighted England's first day of complete dominance in an otherwise disappointing Caribbean campaign as the captain anchored his team to an unassailable position by the end of the third day of the third and final Test against the West Indies at the Darren Sammy Stadium in St Lucia on Monday.

Root's workmanlike 111 not out off 209 deliveries included just nine boundaries and typified the tourists' effort to make amends for previous failures in reaching stumps at 4-325 in their second innings, an overall lead of 448 with two days still available to push for a consolation victory having already surrendered the series and the Wisden Trophy with heavy defeats in the first two matches.

With the home side short-handed in the bowling department on the day due to an early injury to Keemo Paul, England took full advantage.

Root had never gone through an entire Test series without at least registering a half-century, and with just 55 runs from the five previous innings against a reinvigorated West Indies team he was due to come good. It happened on a day when a few others in a suspect England batting order managed to get important runs under their belts.

Successive partnerships of 74 for the third wicket with Joe Denly (69), 107 for the fourth wicket with Jos Buttler (56) and 71 so far for the fifth wicket with Ben Stokes (29 not out) ensured that the captain's steadying influence was ever-present from the moment he arrived at the crease midway through the morning session.

Eschewing extravagance he compiled his innings carefully while those around him showed a bit more aggression against a depleted West Indies attack which left much of the burden on the shoulders of fast bowlers Kemar Roach and Shannon Gabriel.

"It's really pleasing to make a start count," said Root at the end of the day. "I was frustrated in the first innings and I'm glad to make it count after getting in. I managed to find ways of scoring runs at times when I didn't feel great but it felt like it clicked today."

A morning of misfortune and misadventure saw England ensuring there was no repetition of the collapses which have defined this Caribbean tour so far, although the early signs were not encouraging.

Resuming at the overnight position of 0-19, the tourists suffered an immediate setback when Rory Burns clipped the first delivery of the morning to Alzarri Joseph at square-leg to give Paul immediate success.

However the young allrounder, drafted into the final XI for this match due to the suspension of regular captain Jason Holder for a slow over-rate offence in the previous match, left the field on a stretcher shortly after as he appeared to suffer a serious leg injury chasing a ball to the boundary.

West Indies did not help their increasingly difficult situation when Shimron Hetmyer put down a simple chance offered by Denly off Gabriel.

England lost Keaton Jennings midway through the morning when the left-hander attempted to turn a delivery from Joseph top the leg-side and the ball ricocheted off his body onto the stumps to send him back to the pavilion for 23.

If West Indies felt they had opened a doorway to the vulnerable core of the England batting they were left disappointed as Denly, mindful about increasing questions over his credentials as a Test batsman, played fluently after his early life. However Gabriel had the last laugh when dismissing the Kent batsman to a catch at the wicket in mid-afternoon.

Like Denly before him, Buttler played the role of the aggressor in his century stand with Root until Roach produced an unplayable delivery to breach the batsman's defences in the final session and claim his 18th wicket of the series.

Stokes then followed the trend of those who preceded him, ensuring Root reached three figures and leaving England with the luxury of contemplating a declaration at some point on the fourth day.