Hallo...Chamberlain made 3 flights to Germany, the first to Munich to meet Hitler at Berchtesgaden in L.10 G-AEPR, the second to Cologne to meet Hitler at Bad Godesberg in the brand-new L14 G-AFGN and the third to Munich for the multinational Peace Conference in G-AFGN again. A back-up aircraft was flown on all these trips
I've summarized what video and still material I could find on the net about Chamberlain's flights in post #64 (4 down) on this link
Great Scoops From Flickr And LIFE Archive - Page 3 - Key Publishing Ltd Aviation Forums
my favourite stills are from the second trip (to Cologne for Bad Godesburg) which show the crew well
http://upload.wikimedia.org/wikipedi...r_Abkommen.jpg
and
http://upload.wikimedia.org/wikipedi...r_Abkommen.jpg
I don't know if your Grandfather was on that trip... I suspect the smaller pilot? in the centre of the latter pic is Reinhold Caspareuthus, a South African...hope these are of interest