The 24-acre West Barnes Lane site is 10 minutes from the main Wimbledon school - which has another 17 acres - has already been extensively improved by Speedcut.
Last year the company carried out complete drainage and laser-levelling on three football pitches and moved and rebuilt a cricket square, creating six new wickets.
They also built a 52,000 cubic metre water tank which will hold extracted water from nearby Ply Brook to irrigate the pitches.
"The site is on a flood plain," says West Barnes Lane manager, deputy head groundsman Miguel Pimenta, who has been at the school for nine years. "Being on clay meant they just became unplayable after heavy rain.
"But thanks to Speedcut the pitches played beautifully during this last winter and the cricket square has bedded in well and the first few matches of the season were played on a very high standard square.
The King's College School job last year was completed by mid-July - a tough deadline, having been started on June 10 and finished on July 22. The first game was played in early September.
Miguel is in charge of the West Barnes Lane grounds and was previously at St. Paul's School, Hammersmith.
"It was a tight schedule because we had our first games scheduled on the newly-drained, levelled and seeded pitches for end of the first week in September," says Miguel, who has just one assistant groundsman on the West Barnes Lane site - Damion Meech, who was previously at St. John's School, Leatherhead.
"There is never a dull moment on our sports grounds," says Damion. "They are in use most of the year and the new drainage and levelling allowed the surfaces to be more playable after bad weather."
The West Barnes Lane site is also home to a sand-filled artificial hockey pitched used by Wimbledon Hockey Club, who are creating a new sand-dressed Tiger carpet hockey pitch on the site of a former football pitch next to the existing hockey pitch.
There are also three rugby pitches and a combined rugby/football pitch at the site. Three years ago the West Barnes Lane site was being used as a training ground by Fulham FC Academy players.
This year a new pavilion is to replace the current ageing building, making the whole site a showpiece sporting centre.
Speedcut Contractors laser-levelled the new rugby pitches using Speedcut's state-of-the-art TopCon laser-guided Caterpillar D6 and drainage was carried out with the Mastenbroek trencher and pipe-layer, then cultivated and seeded with Barenbrug BAR7 ryegrass mixture.
After 12 weeks of grass growth the rugby pitches will be sandbanded and 420 tonnes of sand applied Barry Pace, Speedcut contracts manager, says: "We have a great relationship with the King's College School team and the new rugby pitches will make a big difference to their very busy sporting calendar - which could be hampered by very wet weather in the past.
"King's College School has excellent sporting facilities and we have been delighted to be part of the team giving pupils vastly improved surfaces to play on."
With new rugby pitches, improved drainage, irrigation and better surfaces, the hard-working West Barnes Lane team are hoping they can more easily cope with the intense year-round demands on the site.
Miguel says: "We pride ourselves on producing the best playing facilities of any school and we have to battle through all weather conditions."
At the King's College School main site head groundsman Steve Wells also has assistant groundsman James Waller.
Head gardener Martin Dimon is assisted by Barry Frost and they keep the surroundings in immaculate condition.
"Appearances and good playing surfaces are vital," says Steve. "Kings College School has a reputation for excellence and the team work hard to maintain high standards."