Reply from Neil Walkingshaw, General Manager at MEDesign:

Dear Mr Clark,

Many thanks for your post on the subject of hingelocks and older Backfriends. Your comments are appreciated but the new hingelocks WILL fit all Backfriends (even very old ones).

On very old Backfriends such as yours there is a slight amendment to the standard fitting instructions. Take the two pronged part of the hingelock set. At the base where the prongs are connected, there is a small v shaped grove/snap line. Flex the prongs (or you can carefully cut along the grove with a pair of scissors) until they separate into two parts - remove any sharp edges created from the separated parts.

Insert prongs through the backrest and then fit as per the diagrams on the fitting instruction leaflet (enclosed with the parts) but using the upper groove on the locking component.

Hope this advice helps.

Original post from Peter Clark:

Regretably these do not fit my backfriend.
The holes are too close together.
I am frelying on my old brass hingelocks.
Maybe my backfriend is an older model although it still fulfils its purpose.