First class, second class, and their Recorded equivalents only cover the DIRECT cost of replacement. And not any consequential loss or cost. Up to a value of ten times the cost of a first class stamp. The Direct cost of replacing the ticket, is just a piece of card and a bit of ink. It isn’t the cost of a new ticket. To cover that, you’d need Special Delivery with additional consequencal loss insurance. Remember, if the ticket is lost, the direct replacement is a reprint. But it’s the consequence of the loss you want covering. So you need consiquential loss insurance, which is only available on Special Delivery. Cash, and certain other items, are not covered in First, Second (or their Recorded equivalents) regardless.
Don't think so. A ticket is clearly worth more than just paper and ink, as it would be illegal to produce a forged copy using alternative paper and ink. You have to legitimately acquire it by paying full price for it.
There is nothing in Royal Mail's terms that limits liability in the way you have suggested (to the direct replacement cost of the materials of what has been lost), or to ten times the postage used. The limit is £20 for first or second class regular postage.
In fact,
their website specifically gives the example of a pair of jeans. If it was lost when sent by the original manufacturer, whom it cost £10 to produce, they can only recover £10, even if they sold it to the shop for £20. If it was lost when the shop sends it to the customer, they can only recover £20, which is what they paid for it, even if they sold it to the customer for £25. And thus only the customer can recover the full £25 (of course subject to the usual £20 limit for regular post).
In the same analogy for rail tickets, the factory that produces the tickets would only be able to recover the likely tiny cost of producing the tickets, say 2 pence per ticket. If the factory has then sold them to the train company for 5 pence, the train company can recover 5 pence if the tickets are lost en route to being sent to the customer. If, in turn, the customer has paid £20 for the tickets, then even though they cost only 2 pence to manufacture, they would be entitled to compensation on the basis that their direct replacement cost is £20, if the tickets are lost en route to be posted back to the train company.