Hey Nick, welcome to the site. You should be able to get the info from this link http://www.weatheronline.co.uk/cgi-bin/akt...mp;x=13&y=8
Click on Gravesend which is probably the closest weather station to Erith, then select history and you can set the parameters, i.e the amount of weeks from whatever starting date and you can see what the maximum temperature was on each day. I hope this helps!