FTSE 100 historical data download

FTSE 100 index has been introduced on 3 January 1984 at the base level of 1000. From Yahoo! Finance you can download FTSE 100 data back until 2 April 1984.
Alternatively you can check out these 5 year charts of FTSE or 10 year charts of FTSE.

Steps for downloading FTSE 100 market data

You should see a page similar to this:
FTSE 100 historical data page on Yahoo! Finance

Step2: Scroll down to the bottom of the page and click "Download to Spreadsheet". (By using default settings you will download EOD FTSE 100 data from the broadest date range. If this is not suitable for you, you can modify settings.)
"Download to Spreadsheet" button on Yahoo! Finance

Step3: Most browsers open a file chooser window to select where to download data. Start downloading market data by selecting a file and a location in this window. (Default file name is "table.csv" which isn't too good for identifying historical data on your computer so renaming file to "ftse_100.csv" or similar is advised.)

If FTSE 100 data file is automatically opened with MS Excel or similar software (eg.: Libre Office Calc), it may cause problems when importing data file into a particular analysis software. In this case you should right-click on "Download to Spreadsheet" link (like in Step 2) and choose
  • "Save target as..." in Internet Explorer
  • "Save link As..." in Firefox and Google Chrome
  • or something similar in the context menu (depending on your browser)

You can analyze this data using eg.: Chartoasis Sesame or this free technicalanalysis software.