If you read the various posts on the forums across this site, twitter and facebook it appears those reservations didn't mean much at all.
Tesla have done exactly the same thing with every previous launch - highest value/profit models first, and every time there have been disappointed customers who, it has seemed, want to have their low-end model, even if it bankrupts Tesla ...
Anyone who placed an order right at the start of May, barring "rare option choices", will likely get their car by end July, as against end June for the very first few - not a lot of difference. Within that Tesla is likely to prioritise highest value/profit models, no shame in that, they need money, and within those I can't imagine that any reservation holder, who placed an order in early May , won't be prioritised - although if they can't get the cash together in time or some other complications I wouldn't be surprised if their delivery gets pushed back. Tesla need the money. Tesla didn't rush to assign VINs to Orders, so Tesla have been able to assign VINs "late on" to accommodate reservation holder who were slow in making an order after 01-May, but Tesla have allocated VINs now, so "there comes a time"
Also, it appears that Tesla speculatively produced the cars, rather than "to order". So there will be some option-choices where there aren't enough in the early batches to satisfy demand. Unfortunate for anyone who wanted one of those and doesn't get it.
in USA shortly after launch Tesla also favoured existing owners (i.e. MS / MX) wanting to buy M3 (who hadn't already got a reservation). That makes good business sense to me, because existing customers repeat-ordering make good ambassadors. I have a mid-July delivery date,I didn't make a reservation, I placed my order promptly after 01-May; but I am an existing owner, so either a) the USA experience also holds good in UK or b) the actual conversion of reservations to orders wasn't generating sufficient demand. I took the call from Tesla when it came (I've heard people saying "I didn't recognise the caller ID" or "I was out/away/abroad") ... I also filled in all the forms that they requested immediately. Anyone not able to respond promptly may have got bumped I suppose ...
For anyone wanting an SR- then that isn't available yet. I can imagine some people wanting SR- will cancel their reservations as a consequence, which is a pity of course, but hopefully once the SR- (or something else at that price-point) is available they will become a buyer.
There is another factor in play, which is that Tesla need to manage their share price, and to do that they need good enod of quarter results, and to that end they need to ship maximum cars within easy delivery distance, i.e. USA / Canada, at the end of June. So there won't be any/much manufacturing for EU/UK during June, so that means not many deliveries during August for anyone that missed the July slots.