At this point I have to give credit to Midnight Rambler, as I have based this whole series on one we completed back in 2014 in Crowborough, so thank you for the original idea.
Several of the caches in the series will contain Cluedo cards (from the 2005 version of the game). As per the board game, you need to discover who committed the murder, with which weapon and in what room. With this information, the location of the bonus cache can be calculated. Please let me know if any are missing, and please do not remove any of them.
You're welcome to complete the series in either direction, but it's easier to pick the path going from #11 to #13 than it is to go from #13 to #11. Bonus clues have been set such that both directions lead to the answer in about the same time, and there are two of each card to help ensure you can calculate the its location. If you have no interest in locating the bonus cache, you can ignore this part completely.
This cache contains some Cluedo sheets to help you with your notes as you progress. Please only take what you need, and let me know if the stock is running low.
If you do not know the basics of a Cluedo game, you need to cross off possible suspects, murder weapons and locations by finding cards. The missing suspect, weapon and room are the answers you seek.
Welcome to Greatwood Estate.
Unfortunately, you have arrived a bit too late to meet Dr Black. He has just been murdered. The 29 year old victim was the nephew of the late Sir Hugh Black, the previous owner of Greatwood Estate.
Orphaned at an early age, young Dr Black was brought to Greatwood Estate to be raised by his uncle. Sir Hugh, however, had no idea how to deal with a child, so he sent the young Black off to the finest boarding school in England. During holidays, his housekeeper Mrs White tended to the boy.
Young Dr Black worked hard in school, earned his doctorate in anthropology and returned to Greatwood Estate after his uncle's death. The never-married Sir Hugh had placed his estate in a trust, to be inherited by his nephew on his 30th birthday.
Soon enough, Dr Black discovered a stready trickle of "allowances" from his late uncle's estate to unknown persons, for unknown reasons. Had Sir Hugh been blackmailed? Did he support a secret cause?
Or was it something far more shameful? Dr Black vowed to get to the bottom of these murkey dealings. To that end, he invited Sir Hugh's former associates to Greatwood Estate for a weekend visit. It was during this weekend, with all of his colourful guests in attendance, that Dr Black was murdered.
To solve the murder, you will need to search for clues hidden throughout the Estate. Within this cache you should find a detective notebook that you can use to keep track of your findings. (Please only take what you need.)
The suspects:

Colonel Mustard, a frequent guest at Greatwood Estate, was an old acquaintance of Sir Hugh. He later befriended Sir Hugh's nephew, Dr Black. Although Mustard's military career was not undistinguished, he was more of a legend in his own mind. After retiring, Mustard convinced a publisher that his military exploits would have made a good book. Having received several advance payments, he has only produced one chapter. Meanwhile, his creditors hound him in search of due payments.

Young Green received his 'calling' early in life. At the age of 12, he began preaching at revivals and later took to calling himself 'Reverend Green'. While travelling in England, spreading his own version of 'rob from the rich and give to the poor', he met Sir Hugh and his nephew Dr Black. Rumour has it that the police have questioned Green regarding allegations of fraud, smuggling and money laundering.

A social 'butterfly', Mrs Peacock dabbled in the theatre and dreamed of a career on stage. She was forced to leave England after her involvement in a messy romantic triangle with two important political figures. While travelling in the United States, she befriended Margaret Black, mother of Dr Black. Widowed three times, she has one daughter, Miss Scarlett. Because of Peacock's lavish lifestyle, her late husband's fortune is now nearly exhausted.

An expert in ancient Mid-Eastern history. Professor Plum gave up teaching for high adventure in Egypt. Sir Hugh funded several archaeological expeditions for Plum, and it was through Sir Hugh that the Professor met Dr Black. Not long ago, Plum was accused of plagiarism and summarily dismissed from his job at the British Museum. Much of Plum's writings has allegedly been 'lifted' from the notes of a colleague who had been killed in a freak accident.

Seductive Miss Scarlett is the daughter of Mrs Peacock. With jealousy and envy the foundation of their relationship, the two seldom speak. An aspiring actress, her ambitions far exceed her talent. Her career in a tailspin, Miss Scarlett focused her attention on a brand new interest - rich old widowers. As a result, the London tabloids had a field daycovering her exploits. To avoid more bad publicity, she reluctantly joined her mother for a long holiday at Greatwood Estate.

Mrs White was Dr Black's long-time housekeeper and cook. When he first came to live at Greatwood Estate as a young child, Mrs White served as his nanny. She was one of the few employees Dr Black retained after his uncle's death. As cook, Mrs White enjoyed experimenting, although dinner guests often viewed her menues with great apprehension. Now 63, Mrs White appears to have little to show for her years of dedicated service.
Good luck.
Congratulations to nicksp8 for being first to find.
The landowner (Forestry Commission East England) does not assess the suitability or safety of the cache location. The cache placer and the cache finder have a responsibility to take reasonable precautions to protect their own safety and the safety of others. Hazards observed at or on route to the cache location should be reported to the cache owner. The cache is placed in accordance with the Forestry Commission East England agreement.
Cache made Premium Only in an attempt to protect it from the sabotage affecting a large portion of this series.