I bought a National Savings poster for £50 as I liked the design. The poster features a little mouse, with a bigger shadow in the background with the slogan: Double-Up Your Savings.

It has a sort of War-poster like vibe and I'll eventually get it reframed, and have it mounted in my home office.

The only information I have is what you can see on the poster - it was printed by a company called Fosh and Cross Ltd. 

I've had a dig around the depths of the internet looking for a similar poster, but cannot find it anywhere. 

I'm not looking to sell, but was wondering if you could give me a rough estimate of what it might be worth. Even if it's under £50, I don't mind, as I love the poster - I think it has character. 

Dan Hatfield, resident This is Money valuation experts, replies: There's something  delightful about this poster... it feels quintessentially British. 

A serious subject, handled with a playful touch. Perhaps it's our British reticence when it comes to discussing money that inspired the designers to adopt a more light-hearted approach. 

A subject deemed impolite to mention in polite society was made approachable and engaging, and the this poster succeeds - and continue to succeed - in that mission.

NS&I (National Savings and Investments) in its earliest form was established in 1861 to help the government manage its deficit. 

As of 2017, approximately 9 per cent of the government's debt is serviced through NS&I and its various products. 

Placing one's savings into this state-backed institution has proven immensely popular, particularly as all deposits are fully guaranteed by HM Treasury.

It's interesting to note that the original aim of NS&I, aside from assisting the Government in servicing its debt, was to help the public 'provide for themselves against adversity and ill-health.' 

This reflects the context of the 19th century, a time before benefits, universal healthcare, and state-funded pensions existed. 

Individuals were largely responsible for their own financial security in the face of illness or job loss. 

Such a scheme would undoubtedly have appealed to many, and it remains attractive today from a purely money making point of view. 

From the Government's perspective, NS&I kept the wheels of the state turning, and it was during the First and Second World Wars that the institution's role became even more crucial, playing a significant part in financing the war effort.

It was during the First World War that we first saw the emergence of National Savings products, including war bonds. 

The Government was in desperate need of funds to continue financing a war. 

Again, during the Second World War, the public was encouraged - through posters like the one in question - to use NS&I to support the war effort. 'Lend to defend' became a rallying cry.

Now, to your poster: There is no mention of the war in its design. From this, we can deduce that it was not created during the First World War, and the absence of any reference to the Second World War similarly suggests it wasn't produced during that period either. 

Having encountered numerous NS&I posters at auctions, I must admit I've not come across this particular design before. 

Curious, I contacted NS&I for clarification, and its response was intriguing. it indicated that, after some investigation, it found no record of this poster and no copy in their archives. 

However, it did identify a few other posters featuring the same National Savings flag, dating them to 1949.

Posters from the mid-1950s and 1960s tend to feature more mature themes, such as landscapes and people, rather than whimsical illustrations like the mice in this one. 

Based on this, I believe your poster was likely created between 1950 and 1955. My theory is further supported by the fact that the poster promotes a scheme where lenders could double their money, a selling point heavily advertised in the 1950s and 1960s. 

Typically, over a period of 10 years, savers could double their investment through accumulated interest.

Valuing an item with so little documented history is tricky. It's possible this poster was produced in limited quantities. 

After reviewing past auction results, I found no record of a similar item being sold. I find myself intrigued, perplexed, and excited by this discovery - it's quite a challenge to determine its value.

Normally, I would estimate an original NS&I poster similar to this at around £40 to £60 - roughly the price you paid. 

However, given its rarity, it might perform well at more specialist auction. Enthusiasts of NS&I memorabilia may be willing to pay a premium for such an uncommon find, so I'd suggest an estimated value closer to £100 - or potentially more.

In any case, it's a fun and vibrant poster that has certainly kept this valuer scratching his head. Whether you choose to sell it or simply enjoy it, it's a fascinating piece with a rich history.

Send in your Modern Treasures

Dan Hatfield is This Morning's money-making expert and resident pawnbroker. He is an international specialist in antiques, jewellery, diamonds and collectibles. 

Dan's first non-fiction book, Money Maker: Unlock Your Money Making Potential (£16.99, published by Hodder Catalyst) is available now.

This is Money's Modern Treasures column is after your items and collections for valuations. 

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Dan will do his best to reply to your message in his bi-weekly column, but he won't be able to answer everyone or correspond privately with readers. 

Nothing in his replies constitutes regulated financial advice. Published questions are sometimes edited for brevity or other reasons.

As with anything, if you are looking to sell items and collections, it is wise to get a second and third opinion - not just rely on Dan's suggestions.