Brits' reliance on their mobile phones means they are struggling to remember important telephone numbers off by heart, says CPP.

Research by the life assistance company revealed nearly half (47 percent) of Brits can't remember their partner's mobile phone number, while 61 percent can't recall their best friend's number. Furthermore, 45 percent don't know their parent's number off by heart.

CPP also said that in an online memory test designed to assess the nation's ability to recall sequences of numbers, four in five Brits could not remember a random mobile phone number after just five seconds.

Nearly two thirds (67 percent) said they were concerned about losing the number stored on their handset, yet just 43 percent have a backup of the numbers in an address book, while 18 percent also store the numbers on their PC.

"Brits' inability to recall numbers of their nearest and dearest means that many could be in a very tricky and distressing situation if their phone is lost or stolen, if they have no idea how to contact someone for help. This shows us that mobiles have literally become people's lifelines," said Michael Lynch from CPP.

"Even if not caught in an emergency situation, our research shows that four in 10 victims have admitted that they've lost contact with friends when they've lost or had their phones stolen."

Over half of Brits (53 percent) can't remember their bank account number, while 44 percent struggle to recall their national insurance number. However, 92 percent can remember their landline number and 60 percent can recall the home telephone number of their parents.

34% of Brits have used text speak when writing