50 minute layover in Calgary (from Victoria) to London UK - is it enough time?

It's enough time to transit the airport, but does have the risk of misconnecting due to flight delays.
AC or WS? Which flights? We can look at historical performance for the incoming flight on sites like Flight Aware.

You're at the mercy of whether your first flight arrives on-time. YYC isn't that big of an airport, and one could reasonably get from one end to the other in 10-15 minutes. That said, 50 minutes doesn't give much allowance for delays.

l69norm wrote: ↑ 50 mins layover but the gate closes 15-20 min before departure plus the time needed to deplane from your first flight if you aren’t at the front, say 10 min. You really only have 20-25 mins max

The flight likely will have already started boarding

Still waiting to hear which airline.
If it's AC, there's likely an alternate same day connection available that the OP can be protected on via YVR if it appears that the YYC flight will be operating late. My risk tolerance would likely be fine for this connection, provided that a reasonable same day reaccommodation option is available on the flight date. I would definitely keep a close eye on the flight status that morning, including the incoming flight, using a site like Flight Aware.

But it's more likely that OP is travelling WS, since AC's YYJ-YYC flights end next month.
If WS, it's unlikely that there are any same day protection options. Plus, WS staff in YYJ are contractors and can't easily issue ticket reroutes without calling a help desk and waiting on hold which they are often not willing to do at the gate. I would be much less comfortable with a 50 minute connection to a destination that's infrequently served on WS. Since WS has a robust flight schedule YYJ-YYC, I'd definitely take an earlier connection.

tofinoguy wrote: ↑ But it's more likely that OP is travelling WS, since AC's YYJ-YYC flights end next month.
If WS, it's unlikely that there are any same day protection options. Plus, WS staff in YYJ are contractors and can't easily issue ticket reroutes without calling a help desk and waiting on hold which they are often not willing to do at the gate. I would be much less comfortable with a 50 minute connection to a destination that's infrequently served on WS. Since WS has a robust flight schedule YYJ-YYC, I'd definitely take an earlier connection.

Not to mention, WS' willingness to aid passengers in these circumstances is next to zero these days, even if a schedule change is involved.

... which is another point to ask the OP - was there an itinerary change that led to this? Or did you book it this way?

I have done it before in a 1 hour connection, in from Comox, to Calgary, to AMS. I was sweating as you, but it worked out okay, even though I was on different tickets (using up points). On the flight from Victoria, book a seat up near the front so you get off early. Know beforehand what gate they normally use. Check an airport map, and use that golf cart service they have on site to get you to the gate quicker. Enjoy your trip, and be aware of the strikes in London, if they are ongoing, for transit systems.

I wouldn't risk a 50 minute layover, particularly in winter, particularly at a busy time like this for holiday travel. It only takes one delay for any reason and you're in a minefield.

We usually design our connections for at LEAST a two hour gap, especially when connecting to flights overseas that might only operate once or twice a day. And still we've had delays and missed connections due to things like inbound or outbound weather conditions, late arriving aircraft, a shortage of ground crew at the arriving airport, mechanical issues with the aircraft, last-minute repairs in the cabin (once on an AC flight to YYZ), the list goes on.