A new study suggests that a fifth of all grandparents in the UK use social networking sites such as Facebook, Twitter and LinkedIn.

Of that fifth, almost three quarters said that they use Facebook, a third use Twitter and almost 10% were on LinkedIn.

As reported in today’s Telegraph, MyVoucherCodes.co.uk carried out the survey from its customer database, and 1,341 grandparents over the age of 60 responded on their use of social networks.

Almost 70% said that they had joined a social network in the past year, whilst over half of those said they had acted on encouragement given by younger people in their families. The desire to connect with old friends was also given as a reason for joining.

These results indicate that around 1 in 7 grandparents over 60 use Facebook in the UK. Not an entirely unbelievable statistic in itself, as half of the UK is now on Facebook, but given that the sample in the survey was taken from people who already actively use the Internet, it may not be entirely representative of the nation as a whole. Just last year Age UK claimed that 70% of people over the age of 65 have never connected to the Internet.

But the overall trend is that Internet uptake is growing more in the older age groups. The UK Internet audience grew from 36.9m in May 2009, to 38.8m in May last year, and more than half of this growth was attributed to those in the over 50 age group.