In answer to the question why apply for the injunction now?
The answer's in the Intranet news item:
"...The Trade Union and Labour Relations (Consolidation) Act 1992 requires unions to send everyone eligible to vote details of the exact breakdown of the ballot result. This point of law was clarified in April following Network Rail’s successful application for an injunction to stop a strike by the RMT..."
So it's a point of law that post-dates the March strikes.
If it does become an illegal strike, that'll be a horrible feeling of deja vu for Tony Woodley, thinking back to the Gate Gourmet events a few years ago
(2005 was it?).