Yeah I'm guessing it changed over the 2012/2013 closed season, I remember a few rainy days working there during Fright Nights 2012 and don't remember any return tickets, but remember at the start of the 2013 season that we were giving out the tickets when it was snowing pretty bad.
Chessington also offer this, although
Legoland do not. Interestingly, Towers make no mention of the weather even having an effect on any of their rides on the easy parts of their website, the only place where anything is said is in the Terms and Conditions:
'4. ATR will endeavour to ensure that as many rides and attractions as possible are available for use by visitors. We may, however, without refund or compensation, change the operating hours of the Resort in its entirety or any part of it; close the Resort in its entirety or any part of it; temporarily restrict the number of persons having access to the Resort or any part of it; and/or suspend or cancel any attraction or entertainment programme, due to capacity, inclement weather, power failure, special events or any other circumstances or grounds which are judged to be necessary to ensure the safety of guests and staff'
Of course, that's only to cover their own backs. Even more interestingly, it specifically later states:
'Alton Towers reserves the right to transfer tickets to another date at any time or offer an alternative ride in case of ride breakdown.'
So that makes it sound even more like it's to cover their own backs - if they have the right to, why not just offer it to everybody? I mean, they might be offering it to everybody, I don't know, but I'm sure if they were they'd have it plastered on their site like Thorpe and Chessington.
Looking at a few more UK parks brings about similar results. Flamingo Land only has a line in their T&Cs about weather affecting rides, and does not even give a slight mention to transferring tickets to another day. Oakwood is similar to Flamingo Land, but it at least warns that rides may close due to weather in their FAQs. Drayton Manor doesn't say anything at all on the subject, and doesn't even have any T&Cs or FAQs on their website.
One last interesting thing that I noticed when looking through T&Cs is parks positions on plaster casts. Going off topic, sure, but I doubt it warrants it's own topic.
Flamingo Land states in their FAQs that guests with casts would be unable to ride the majority of their rides.
Drayton don't say anything about it because their website is evidently crap.
Thorpe Park, in their Ride Access guide, first say that guests with casts are unable to ride anything at all, then literally 2 bullet points later say that guests with casts are only advised not to ride.
Alton Towers says that those wearing casts may ride some, but doesn't give any indication as to what the rides are, and while I'm sure most people would be able to put two and two together, it does provide a small loophole.
Chessington offers a detailed list of what rides a person with a cast can ride, dependent on where the cast is on your body. Weirdly, a guest with an arm cast can go on Tomb Blaster, but a guest with a leg cast cannot. I guess it's for evacuation purposes, but it still strikes me as a little odd.
Legoland also gives you a list on what you can and cannot ride specifically, although doesn't indicate a difference between upper body and lower body casts.
Oakwood, however, doesn't give a **** and says as long as you can brace yourself, go for it cast boy.
Anyway, off topic bit over and in an attempt to link it all together, it seems as though all the main UK parks, even the ones owned by the same company, have many disparities within their T&Cs and how they operate, whether it's to do with the weather or even something like casts.