Helo IFR in the UK
Just so to clarify, it's not clear to me whether these gentlemen had an IFR flight plan on file and if so how soon would they have been able to maintain IFR obstacle separation legally if not departing from protected airspace.
By protected airspace I mean an airspace where obstacles have been surveyed not to intrude in a certain slope gradient around a defined location, to allow for departures and arrivals under not so much IFR but IMC, with adequate and published procedures.
Even in the "sporty" USA, pilots are required to maintain obstacle separation until reaching the airspace above where they can legally be IFR.