People across the globe delving back through history frequently find they have ancestral links to Norfolk.

Historical events throughout the centuries have led to countless people moving in and out of the county and as a result many people – including the Duchess of Cambridge – can trace their roots back to Norfolk.

Local history researcher Gill Blanchard, who has an office in Queen's Road, Norwich, knows more about the subject than most and this week she is giving a talk about Norfolk ancestors at what is dubbed the biggest family history event in the world – the Who Do You Think You Are? Live 2012 event at London's Olympia.

Ms Blanchard, 51, who has published a book called Tracing Your East Anglian Ancestors, is frequently contacted by people overseas whose family history trail has led them to Norfolk.

She said: 'People contact a researcher because they want experts to help them access information that seems inaccessible to them. About a quarter of my clientele is from overseas – a large number of Americans and Australians, some South Africans, a lot of Canadians, and people from the former colonies.'

She said there were key reasons that linked Norfolk with places across the world.

'There is a surprisingly large amount of people with Norfolk ancestors because it was Britain's most populated and richest county in the late 1700s and early 1800s before the industrial revolution arrived – all based on its thriving wool trade,' she said.

'Norwich was also the second city after London during the medieval period and its influence and people spread far and wide.'

Norfolk had been the site of major ports – including King's Lynn and Great Yarmouth – and has had trade links to the continent throughout history which, said Ms Blanchard, which also contributed to the county's importance with people moving both to and from Norfolk. When the county's trade declined during the industrial revolution people living in Norfolk moved elsewhere in the United Kingdom and abroad.

Migration of people searching for new opportunities also played a big part in Norfolk people moving across the world.

Tracing a family line back through the generations can be a long and laborious process and involve trawling through documents including old marriage certificates, parish registers and census records.

Ms Blanchard, who lives in Hotblack Road, Norwich, said when starting out people should take stock of what they already know.

'You have to start from what you know and work backwards,' she said. 'The obvious thing is to start with talking to your relatives. Find out about family stories and whether your relatives have any copies of birth, marriage and death certificates – they are seen as the building blocks of family history.'

It is important to keep a record of every bit of research and the documents looked at, she said. Cross reference all information and keep photographs of relevant documents.

'I am a huge fan of family history societies,' said Ms Blanchard.

'You have got a lot of very keen and knowledgeable volunteers who have collected together lots of useful information and by contacting them you are tapping into a great pool of information and knowledge often at a very miniscule cost.

'The Norfolk Family History Society and the Mid Norfolk Family History Society are both very active organisations,' Ms Blanchard said.

Other great resources include the Norfolk Record Office at County Hall, which preserves Norfolk records from the 11th century onwards, including documents from families and individuals, local authorities, churches and other organisations.

The Norfolk Heritage Centre at the Millennium Library in the Forum is also a good source of information.

Ms Blanchard said the internet was another brilliant resource.

'It has opened up family history research to many more people and there are a huge resources online like the Norfolk Online Access to Heritage website, and the Poppyland Publishing website,' she said.

And while researchers should stay focused and disciplined in their approach, Ms Blanchard said it was important not to be tunnel visioned –a small diversion could lead to the most interesting of discoveries.

Ms Blanchard is a member of the Association of Genealogists and Researchers in Archives (AGRA), the only organisation that accredits genealogists in the UK.

Her book Tracing Your East Anglian Ancestors: A Guide For Family Historians costs �12.99. For more information visit www.pastsearch.co.uk

She will be giving two talks at the Who Do You Think You Are? Live 2012 event at London's Olympia. Tomorrow, at 12.30pm, she will speak on Norfolk Ancestors: An Insider's Guide, and on Sunday, at 10am, her subject is Top Tips for Writing Your Family History.

For more details on Who Do You Think You Are? Live 2012 visit www.whodoyouthinkyouarelive.com

For more information about tracing your family tree visit www.edp24.co.uk/familyhistory

Other useful websites are www.noah.norfolk.gov.uk, www.norfolksources.norfolk.gov.uk, www.poppyland.co.uk, www.norfolkfhs.org.uk and www.tsites.co.uk/sites/mnfhs

emma.knights@archant.co.uk