"Can you still buy a Mangle like my gran used to use with her twin tub waching machine back in the 1970s."

Yes, you can. For example, Lehman's (lehmans.com) carries two models that clamp onto your washtub. I have one that resembles their less expensive model; found it elsewhere online for about $110, under the name Dyna-Jet. Very useful for t-shirts, socks, underwear, towels...anything that doesn't have buttons or zippers.