I'll second Robo's thank you to the more technically knowledgeable mermen here present! I'm assuming from the comments already passed that, regardless of any cynicism about the poltico's, we're accepting this as an accurate & objective inquiry on what happened?

A quick search for more info on the Upholder class produces this, which appears to be official Canadian Navy spiel.

This is rather less complimentary, but appears to be generally anti- military procurement, rather than "Don't buy Upholders, they're inherently crap" which was an early suggestion in this thread.

Here we have more what I was looking for in response to Robo's admission of ignorance (mea culpa, me too!), the relevant para being:

The UK's Upholder (Type 2400) class submarines were built by Vickers Shipbuilding and launched in the late 1980s and early 1990s. They were withdrawn from service in the British Royal Navy in 1994, following a defence review by the UK government. Canada purchased the submarines and a suite of trainers in 1998 and BAE Systems (formerly Vickers Shipbuilding) at Barrow in UK were contracted to refit the submarines. The submarines are being transferred to Halifax in Canada for commissioning.

which suggests that the actual design & technology originates from the early 80's.

My sympathies still lie with Lt Saunders, but it does now look like it was something that amounts more to an 'industrial accident', than to anything blamable on anyone. To put it another way, we can (& have!) rowed endlessly about whether the Iraq war was justified, but some of those who have died were victims of traffic accidents. They might have been victims of traffic accidents without Iraq, & it looks like Lt Saunders was, if you see what I mean.

Sometimes bad luck just happens. :(