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A cookie is a small text file that can be stored on your computer or device when you visit a web site. Cookies are commonly used to keep track of users visits and help make web sites work more efficiently.

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Cookie settings

A link to the cookie settings also appears in the footer of every page of this web site.

Most web browsers allow you control how cookies are managed and delete stored cookies via their privacy preferences.


We use cookies to monitor the use of our web site. This helps us ensure it is operating effectively and find out where we can make improvements. The cookies collect information in a way that does not directly identify anyone. More information about how we process data is available in our privacy policy. The sections below explain which cookies we use and why we use them.


These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. These cookies do not store any personally identifiable information.

Function Cookie name Purpose
Cookie preferences OptanonConsent Stores your preferences about cookie use on the web site.
Cookie alert OptanonAlertBoxClosed Determines whether the web site needs to display a cookie message.


These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.

Function Cookie name Purpose
Google Analytics _ga
These cookies are used to monitor how visitors use our website. We use the information to compile reports and to help us improve the website. They store information about how you got to our site, what you click on, the pages you visit and how long you spend on them. This data does not include any personally identifiable information.

For more information about Google's data practices please read their overview: Safeguarding your data.

You can opt out of being tracked by Google Analytics on all web sites by following the instructions here:


This page was last updated on 17th November 2021.