While most students spend their gap years trekking through the Himalayas or sunning themselves in Australia, Charlotte Tobin opted for more cerebral pursuits.

The 20-year-old ditched the round-the-world trip for the mammoth task of indexing a 340,000 word, two volume, masterpiece entitled Horsham's History.

Her intellectual adventure began when she volunteered to work at Horsham Museum.

Curator Jeremy Knight had just the job for the her and handed over his lengthy historical work.

Charlotte worked full-time as a waitress and one day a week at the museum over the year.

She read through all 340,000 words of the books and noted down keywords, names and subjects for the index.

The finished index runs to an impressive 30 pages and 2,500 entries.

Charlotte, who is studying for a history degree at Sheffield University, said: "When I offered to volunteer I didn't know what kind of job I was going to be given.

"I was pleased to have so much responsibility and I really enjoyed it."

Among the most fascinating facts were the different types of dinosaurs which have been unearthed in the town.

She said: "Dinosaurs, that's proper history. I also learnt a lot about some of the key Horsham families such as the DeBraoses and the Shelleys."

Although enjoying her history degree, Charlotte has different plans for the future, including travelling round Australia and New Zealand, and training to be a criminal defence barrister.

Her hard work allowed her to save enough money to pay for a two-month trip across North America over the summer.

However, she promised to return to the museum in her Christmas and summer holidays.

She said: "The people are really nice and there is so much interesting history waiting to be discovered.

"That's what I love about history, there's so much of it."

Mr Knight, the curator for the past 19 years, said: "Charlotte has done a fantastic job. It was not an easy task I gave her but she rose to the challenge.

"I spent three years writing the books and never got round to the index.

"I think it's brilliant that someone of her age has dedicated herself for a whole year to such a consuming job and she has done it so well."

The index is available from the museum and is free to people who have already bought Mr Knight's books.

All proceeds will go to the museum's purchasing fund.