1 April 2017 Last updated at 12:33 BST
The tiny pad was appraised by manuscripts specialist Matthew Haley during an episode filmed at Caversham Park in Berkshire.
The programme will air on Sunday at 20:00 BST on BBC One.

The man, 41, was helped from the Audi TT which had been driven at speed into Carr Mill reservoir in St Helens on Monday evening, Merseyside Police said.
Five officers were filmed rescuing him from the slowly sinking vehicle.
The man was found to be uninjured when taken to hospital. He was detained on suspicion of a number of offences.
These included the unauthorised taking of a motor vehicle, burglary, dangerous driving and failing to stop, police said.
Officers started tracking the suspected stolen Audi in Liverpool at about 20:20 GMT.
When police attempted to stop the car, the driver sped off, leading to a police pursuit up the M62.
Officers deployed a stop-stick before the Audi continued to be driven at speed and finally into the reservoir.
The officers who went into the water were also checked over as a precaution and have all been released.
Ch Supt Jon Ward said: "The officers involved in this pursuit and rescue acted with exceptional bravery, tenacity and professionalism to rescue the man on a bitterly cold, wet and miserable evening.
"Without a second thought given to their own safety and the conditions, they entered the freezing water and dragged him through the rear of the car just before it became completely submerged."

18 January 2016 Last updated at 20:09 GMT
Ben Frost, 27, barricaded himself into his girlfriend's flat in Princetown on Dartmoor on 18 January.
He was arrested two hours after breaking through the roof, Plymouth magistrates heard.
Unemployed Frost of no fixed address admitted two charges of causing criminal damage and two of threatening behaviour.

A Vauxhall Astra and a Peugeot 206 were involved in the crash on Blackburn Road in Sheffield at 01:00 GMT.
Joshua Fothergill, 19, of Rotherham was in the Astra and died at the scene as did Liam Parkin, also 19, of Sheffield who was in the Peugeot.
A 20-year-old man, held on suspicion of causing death by dangerous driving and failing to stop, has been bailed.
Three other men who were travelling in the Peugeot were injured and taken to hospital for treatment.
They were a 24-year-old and an 18-year-old from Rotherham, and a 21-year-old man about whom no other details were released by police.

Mr Opstelten had said the trafficker was paid less than he actually was for money wrongly confiscated by the state.
He also said details of the payment - authorised by Mr Teeven as prosecutor - had been lost, but this was not so.
The resignations are a blow to the Liberal party as it faces an election.
Mr Opstelten and Mr Teeven are both from the conservative wing of the party, which faces a challenge from Geert Wilders' far-right Freedom Party in provincial elections this month.
The resignations are also expected to place a strain on the Liberal's coalition with the Labour party, which has been very critical of Mr Opstelten and Mr Teeven.
The justice minister had claimed that a convicted drug trafficker, Cees Helman, was paid much less than the compensation of 4.7 million Dutch guilders - worth â‚¬2.1m (Â£1.5m; $2.3m) in current terms - that he in fact received.
He also said that the details of the payment had been lost.
On Monday, however, Mr Opstelten said a record of the transaction had been found.
"This information could have been found earlier," he told reporters. "I take full responsibility for this and have just now offered my resignation to the king."
The payment was made after the authorities were unable to prove that money they had confiscated from Helman had been obtained illegally. Mr Teeven, who was a prosecutor at the time, had authorised the settlement.
The payment was not illegal. However, both ministers said the misinformation had made their positions untenable, Reuters news agency reports.
A 17th Century notebook analysing the work of William Shakespeare has been described as "extraordinary" by an Antiques Roadshow expert.
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Helicopter footage of officers wading into icy waters to rescue a man who had driven a suspected stolen car into a reservoir has been released by police.
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A man who sparked a drug-fuelled roof-top siege after breaking up with his partner has been given a suspended prison sentence.
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Two teenagers who died when two cars collided in the early hours of Saturday have been named by police.
[NEXT_CONCEPT]
Dutch Justice Minister Ivo Opstelten and his state secretary, Fred Teeven, have resigned after misleading parliament over a 2001 compensation payment to a convicted drug trafficker.