By filling in details of your journeys over FOUR CONSECUTIVE DAYS, you'll help TfL and the Association of Train Operating Companies (ATOC**) plan TfL and National Rail services based on how Travelcards are being used.

Diaries are being distributed at stations and through the post, and can all be returned to the Freepost address provided. Invitations to take part in the survey are also being sent by email.

For each returned diary, a £2 donation is made to charity and proceeds will be split between Asthma UK, The Royal Society for the Protection of Birds, Marie Curie Cancer Care and Citizens Advice Bureau.

** ATOC sometimes uses the name Rail Delivery Group (RDG)

Over the past eight years you've helped us raise more than £431,000. Our latest donation, made in February 2015, shared £7,848 among our nominated charities.

You may receive a Travelcard diary through the post or by email, or one of our surveyors may offer you a diary at a station.

The diaries are simple to fill in and free to return, see below for more detail on completing a diary.

Every diary we get back is useful, so thanks to all of you who have helped out with the previous surveys

Completing diaries

When completing diaries, please remember to:

• Record all trips, including return trips
• Record trips on London Overground as 'Rail'
• Record trips on different modes separately, for example if you take the Tube to Finsbury Park and then change to National Rail, record the trips as separate entries on the diary

Four charities are selected as recipients of the Travelcard survey donation each July. A range of charities are chosen in order to appeal to the public's range of preferences. The charities usually include two health charities, one animal charity and one miscellaneous charity.

Each charity is guaranteed a minimum tenure as a survey donation recipient for one year, and may remain a recipient for a maximum of two years. A working group of stakeholders discuss potential new beneficiaries of the survey and we welcome expressions of interest from both local and national charities.