When did it happen?

Once upon a time Cammel Laird built ships and Grayson and Rollo where ship repairers. Both separate company's doing their own thing.
Then as I recall, the government of the day decided to change things, yards where amalgamated and then things began to fall apart. My impression was that someone in government thought Mersey-side would be a better place without ship building and repair and they had an hidden agenda!
Lairds and Grayson's became one company (name unknown). Eventually, the yards were closed, Grayson's never to open again but thankfully Lairds is still around "a rose by any other name".
Can anyone help with dates and times:
When did the two companies become one?
When did Grayson's cease repairing ships?
When did they start/finish filling in the dry docks at Grayson's Birkenhead?
Any other information on this welcome.