For genealogists parish records, while undeniably useful, are never completely reliable and not just because of the ravages of mould, mice, fire and flood, and the actions of lazy or incompetent priests.
In the 18th century, until matters were tightened up by the 1753 Clandestine Marriage Act (aka Hardwicke's Act), marriages could be performed by any CoE minister, many operating out of unlicensed chapels, which were often just their own house, the local pub and sometimes even debtor's prisons. Going back further, despite numerous laws had been passed saying how things were supposed to be done, but many couples were deemed to be married simply because they lived amicably together (and why not?), often with no formal ceremony ever having been performed beyond maybe a statement made in front of friends and family (and similarly they could be considered divorced, in law, if they mutually agreed to part). Accordingly even before the church lost its monopoly on performing weddings, the recording of marriages was always fairly hit and miss.
For example the marriage record for a couple of my ancestors has survived only by pure luck, as their marriage was unorthodox although not particularly unusual for the time. In 1745 as a young couple (both about 18 years old and so of an age that they should legally have obtained parental consent) they eloped from their home village in rural Sussex and went to London. Here they were married in "St George's Chapel" at Hyde Park Corner, then an unlicensed chapel whose minister (the Rev. Alexander Keith) performed quickie - no banns, no questions, cash in hand - weddings in the parlour of his house, the so-called chapel. This was before the Hardwicke marriage act and so while unorthodox it was still legal as he was an ordained minister of the church. Following the 1753 act the vicar of the adjacent Anglican parish church, also called St George's, moved quickly to get Keith's chapel shut down, his principal grievance being not that the weddings were incorrectly sanctified but that he was losing out on all the marriage fees.
But in 1745 my ancestors, having successfully eloped and married, then returned to their home village - presumably to face the ire of their parents - and settled down to have fifteen or so children together. All their children were baptised in the parish church, and these children later married, and wereburied, there but the original couple who'd married in London never felt the need to remarry there. But going back to records: the only record that exists of their being married at all is the one line entry in the tatty record book kept by the Rev. Keith, that was found (by chance) amongst his personal possessions when in 1758 he died as a debtor in the Fleet Prison (the ledger was rescued by an antiquarian and eventually found its way to the London Records Office).
Marriages (and baptisms and burials) are still recorded by parish churches (and by similar registered venues for other faiths) but since 1837 the principal record of births, marriages and deaths in Britain has been the central registration system operated by the General Register Office in London (and its sister office in Edinburgh). For genealogists this is a far simpler and more comprehensive system especially as most of it is now accessible online. So even if you get married at Alton Towers you still won't evade discovery by future genealogists, and note that under current law you can still only be married in a registered building - you cannot for example be married outside in a garden even if it is attached to a registered building - and a registrar, either an officiating religious official of a civil registrar, must be present.
The French system is that a marriage is only legal once performed by a civil official - typically the mayor of your home town - after which you can have whatever ceremony you want be that in the local parish church, synagogue or mosque, in a bar, on a boat, at the beach, up a mountain, down a cave, or in your own home. For my marriage in France there was just the two of us with the Sous-Préfect crammed into her tiny office in the local town hall, followed by a bottle of champagne on the beach - but that's another story.