Series III 109 Station Wagon Rear Seats Question

My 109 is off for it's MOT tomorrow. It's new to me and am just getting to know it. I think i remember somewhere that all seats should lock in upright position. The second row however do not do this there is no bar behind to attach them to and I can't find any locking mech. Am I right? Should these seats lock? Thanks all
Will

The rear seats do not need to "lock" in an upright position. As long as the bases are securely fitted and the backs do not fall flat backwards, they should be ok.

thank you!