Great work Grumpy.. It will be a smashing day out. Bonus dropping onto that show...
IWM bless 'em they don't make things easy to book up on their site!!!
Try this link to short cut to the booking for this particular show.
https://www.maximweb.net/imperialwarmuseums/events/
Scroll down and select 'IWM Duxford Car Show 2018"
Just click "next" from the date page and enter the SCS18 code.
On the next page tick the £13 ticket box
AND the vehicle pass box, you will then receive a link to download and print both ticket and pass on the confirmation email after you have jumped through the remaining hoops!
Hope that's a bit simpler?