Well let's see.
EC are putting on two extra southbound trains on the Saturday and Sunday, with four extra northbound trains on the Sunday. GC are putting on one extra train each way on the Sunday.
Which sounds fantastic... until you realise that due to planned engineering works, EC are only running 1tph between Newcastle and London, instead of their normal 2tph. So although it's been presented as five 'extra' trains running, it's still quite a reduction on the normal Sunday service.
What is good is that Network Rail has rescheduled some of the work in order to allow some of these 'extra' trains to run. So, yes a big hurrah to the rail industry for managing to do something - but it's not quite the massive increase in capacity that it's been presented as.