Yes ,they are 18 pdr MK IV P, The arrangement between the hubs is a combination of suspension and Traverse,very complicated.I dont think the idea progressed after the MK IV.There is also a MKII gun in the first picture which would have had the Martin Parry wheel conversion fitted.
It looks like salvage from Dunkirk, has the picture been taken in France ?
Rob.....................rnixartillery.