It should be remembered that the definition of 'insider trading'...

It should be remembered that the definition of 'insider trading' is trading whilst in possession of information not available to the market.
SRT have made an announcement that they are looking at a potential transaction. It would be expected that, until a potential transaction is announcement as a 'non-transaction' or full details are announced of that 'transaction' directors and executive officers are prohibited from trading.

So the shares of MW are not available for trading. (It never looks good when someone like MW 'trades' shares at this stage anyway, and it would be suicidal to do so imo (that means 'in my opinion')).

The shares of another shareholder in the upper echelons of the top 20 are apparently not available for trading, given that he has not 'liked' my previous post.

That reduces the shares 'in play' by "X".

Given the nearology of an announcement I cannot for the life of me work out why anyone would sell between now and (potentially) 15/01/2016. However, I am not a financial adviser and you should DYOR (do your own research).
PPS: I've just had a G&T so I can't be bothered calculated "X".
GLTAH (That means Good Luck to All Holders).

Cheers Tangrams
PS: I love this stock!