I have just purchased a used folding bike in England and I cannot get it to unfold. It is a Raleigh and I have unfolded the pedal and even removed the saddle post but the left pedal will not pass the main folding hinge / clasp. I would appreciate any help.
Thanks
Terry

pictures ?

Sock it well with penetrating oil then let it sit for a day or two.

Not sure what you are saying here. Is it possible that you are just doing it the wrong way? Try to start from scratch and watch some films on You tube about how to fold similar bikes.

Some thin oil on all hinges is a good idea.