It's on a knife edge IMO, the data over the last week isn't good, but it could level off over this & next week, although I don't expect that to happen, in which case the argument for delaying the June unlocking becomes so much clearer.
It does seem like pressure is growing to delay, with several experts, some of which are government advisers, suggesting or pushing for a delay, which will make it difficult for the government to say they are following the science, if the data goes the way I expect. The media attention to these calls does give the impression that we are being made ready to expect there's likely to be a delay too.
As they have always said they want each stage of unlocking to be irreversible, and depending on the data getting worst, it would be totally logical to delay until at least the schools break-up for summer, in the hope of avoiding having to reverse it, or even having to reverse on the May unlocking. By that time all adults wanting a jab would have their first jab, and somewhere around 75% would probably have had their second one.
Plus they have an excuse/cover for a delay, in the form of the Indian variant, which wasn't around when the roadmap was published, and therefore isn't reflected in the plan.
Finally, the NHS is already under extreme pressure, as they start to tackle the backlog of non-covid cases, so even a fairly small increase in covid cases will cause major problems, something they will want to avoid.
I think this week will see the chances of a delay tipping over the 50% mark, my gut feeling is they will delay for those few weeks, but I wouldn't be surprised it they don't.
The bigger question is, would a delay be enough, or could we face going back to the stage before the May unlocking.