Thanks again for the responses. I was just trying to understand what Virgin is offering and how it fits with the regulatory requirements. I think I am clear on that now. It seems that they are obliged to offer the £260 for the delay but are offering the 75,000 points or the Select voucher as enhanced compensation so I have a choice of the 3 options.

I agree that a free return trip is generous compensation, given that we did get back to the UK only 3 hours after originally planned and we were seated in PE on the BOS-LHR leg. Unfortunately this came after a series of flight changes, lack of information, misinformation and so on which is why I will not just accept what is being offered, even though I have low expectations of getting anything extra.