Max Tow, what happens is if you're down route, you carry on working. If you do a back to back and you are operating the 2nd half out of LHR on a strike day, you do not operate that 2nd half if you intend to strike. There are no mixes of volunteers and striking crew. It's an impossibility. Trips between strike dates do not require volunteers as they are already fully rostered.
Just by way of a post-script to my last post:
No volunteers need to report for duties between strike dates as the original rosters for non-strike dates are fully manned with regular crew. The animosity is definitely for volunteers, and there is no mix of them with striking crew, for obvious reasons. Some volunteers have been on board during the volcanic ash disruption, but there were no incidents. Striking crew are not savage animals. We have very great differences in opinion, but the vast majority of us do not end up in fisticuffs.
There is also a big problem with using the volunteers. The cabin service in premium cabins is actually the economy service and product. It's not up to scratch and most premium passengers do not want a 1/4 bottle of Chateau Brixton served to them when paying a premium fare.