Time for me to trot out my usual info about guidelines.
They are now that babies are fine on milk alone until 6 mths and do not need anything before that. Before 17 weeks, there is a recognised and potentially serious risk to health.
Before these guidelines were issued - in May 2003 - the guidelines were 4 to 6 mths.
Big change - NOT. However, what was new was robust research to show that the health of the majority of babies is best protected by a 6 mth guideline, and not 'mother's instincts' or 'mother knowing best' - FFS. This does not mean that every baby in the UK has to start solids on exactly the same day, either - some babies will manage solids a little earlier than this, and some will not be interested in them for a little while later.
The guidelines have never been 16 weeks - that was HVs making it up, truly.
The guidelines were 3 mths to 6 mths for a very short period in the 1970s and 1980s (I'd need to look up precisely what years it was, but it was a long time ago and not for very long). What people did, and what their HVs and doctors told them, might have been different.
BTW - I don't think anyone has sued their doctor or HV for telling them something different from official guidelines. They tell people rubbish all the time, as anyone who reads mumsnet feeding threads will know.