[jb]

How then do self saved seed from non hybrids,(you know the sort in seed banks and from Real Seeds) always come true to type, as they're self fertilised, not cloned?

Basically because they have been inbred to produce the variety so the all copies of the genes in these plants are the ones that give the characters we want (for example in purple beans like cosse violet (my fave) all copies of the genes that determine pod colour will be the purple variant).
This is the basis of breeding plant varieties  in that you want only copies of the desired genes so if you find an interesting variation that is passed on to  the next generation the best way to 'fix it' is to keep inbreeding till you get 100% offspring with the variation but at the same time not fixing any deleterious characters (as Norfolk Turkey mentioned inbreeding can also fix  unwanted characters like the high level of deafness that occurs in dalmations)
It always amazes me that this approach has  been used for hundreds of years by amateur breeders before the foundation of the science of genetics to give us many of the heritage varieties that people like Real Seeds are helping keep alive

[The Norfolk Turkey]

Ta very much MoS! Ill let the cat in the greenhouse again - good at tapping and doenst eat plants!! Who'd have thought genes could be so interesting......   

[SidReal]

gee things were all so much simpler before that guy dawin came along
good old spontaneity, thats what I like

thanks for ure help  :happy: