Thanks for your speedy response and tip. below is the contents of the email.
Error: Couldn't run query: insert into `CalendarEvent_versions` SET `Recursion` = 0, `CustomRecursionType` = 0, `DailyInterval` = 1, `WeeklyInterval` = 1, `MonthlyInterval` = 1, `MonthlyRecursionType1` = 0, `MonthlyRecursionType2` = 0, `MonthlyIndex` = 1, `ClassName` = 'CalendarEvent', `Created` = null, `LastEdited` = null, `Start` = null, `End` = null, `Content` = null, `Title` = null, `StartTime` = null, `EndTime` = null, `Location` = null, `EventType` = null, `MonthlyDayOfWeek` = '0', `CalendarID` = '0', `RecordID` = 29, `Version` = 2, `AuthorID` = 1 Unknown column 'ClassName' in 'field list'
At line 400 in /home/sites/sunrise-lettings.co.uk/public_html/sapphire/core/model/MySQLDatabase.php
user_error(Couldn't run query: insert into `CalendarEvent_versions` SET `Recursion` = 0, `CustomRecursionType` = 0, `DailyInterval` = 1, `WeeklyInterval` = 1, `MonthlyInterval` = 1, `MonthlyRecursionType1` = 0, `MonthlyRecursionType2` = 0, `MonthlyIndex` = 1, `ClassName` = 'CalendarEvent', `Created` = null, `LastEdited` = null, `Start` = null, `End` = null, `Content` = null, `Title` = null, `StartTime` = null, `EndTime` = null, `Location` = null, `EventType` = null, `MonthlyDayOfWeek` = '0', `CalendarID` = '0', `RecordID` = 29, `Version` = 2, `AuthorID` = 1 Unknown column 'ClassName' in 'field list',256) line 400 of MySQLDatabase.php MySQLDatabase->databaseError(Couldn't run query: insert into `CalendarEvent_versions` SET `Recursion` = 0, `CustomRecursionType` = 0, `DailyInterval` = 1, `WeeklyInterval` = 1, `MonthlyInterval` = 1, `MonthlyRecursionType1` = 0, `MonthlyRecursionType2` = 0, `MonthlyIndex` = 1, `ClassName` = 'CalendarEvent', `Created` = null, `LastEdited` = null, `Start` = null, `End` = null, `Content` = null, `Title` = null, `StartTime` = null, `EndTime` = null, `Location` = null, `EventType` = null, `MonthlyDayOfWeek` = '0', `CalendarID` = '0', `RecordID` = 29, `Version` = 2, `AuthorID` = 1 | Unknown column 'ClassName' in 'field list',256) line 102 of MySQLDatabase.php MySQLDatabase->query(insert into `CalendarEvent_versions` SET `Recursion` = 0, `CustomRecursionType` = 0, `DailyInterval` = 1, `WeeklyInterval` = 1, `MonthlyInterval` = 1, `MonthlyRecursionType1` = 0, `MonthlyRecursionType2` = 0, `MonthlyIndex` = 1, `ClassName` = 'CalendarEvent', `Created` = null, `LastEdited` = null, `Start` = null, `End` = null, `Content` = null, `Title` = null, `StartTime` = null, `EndTime` = null, `Location` = null, `EventType` = null, `MonthlyDayOfWeek` = '0', `CalendarID` = '0', `RecordID` = 29, `Version` = 2, `AuthorID` = 1) line 418 of Database.php Database->manipulate(Array) line 117 of DB.php DB::manipulate(Array) line 833 of DataObject.php DataObject->write() line 642 of LeftAndMain.php LeftAndMain->save(Array,Form,HTTPRequest) line 228 of Form.php Form->httpSubmission(HTTPRequest) line 107 of RequestHandler.php RequestHandler->handleRequest(HTTPRequest) line 121 of RequestHandler.php RequestHandler->handleRequest(HTTPRequest) line 122 of Controller.php Controller->handleRequest(HTTPRequest) line 277 of Director.php Director::handleRequest(HTTPRequest,Session) line 121 of Director.php Director::direct(admin/EditForm) line 115 of main.php