I don't disagree that different people will have their preferences for LON-area airports, and that slightly more people may prefer LHR to LGW, but it's not a material driver of traffic.

It also has to be offset against the much higher cost of operating at LHR, which would hurt WS's ability to offer competitive fares.

You seem to have misunderstood what I've said. Obviously WS has added partnerships, and those partnerships will drive a certain amount of traffic. But they offer very little to the customer relative to what they could and relative to what WS talked up when they signed the deals. I have no idea how they picked that tiny number of destinations that you listed (and there are a few others, like LIS and OPO), but the fact is that despite a codeshare agreement with one of the largest European airline groups in AF/KL implemented several years ago, WS will not sell you a ticket to the vast majority of destinations served by those airlines.

This thread is about WS at LHR. I suggested that given WS's lack of partnerships, there would not be a lot of connecting traffic for them at LHR. You mentioned a potential VS partnership. But my point is that if, after several years, they've done very little with the AF/KL partnership (and the other partnerships they've signed over the years), a VS partnership is unlikely to drive much traffic for quite some time. No need to start incurring the much higher cost of flying to LHR today just because maybe in 2-4 years you might sell a few connections with VS (I would also suggest there's not actually that great a fit between WS and VS, since VS mostly flies TATL. At most, it looks like TLV, JNB, LHE, DEL, BOM, ISB, CPT might make sense - there's not a lot of demand for connections like YYC-LHR-BOS.)

Outside of (potentially) VS, take a look at WS's list of codeshare partners. For how many of those do connections at LHR make sense? DL, LA, wrong direction (as above, YYC-LHR-BOS etc doesn't make sense). AM doesn't fly to LHR, but would be the same thing. QF is also the wrong direction, albeit the other way. The Asian carriers (CI, CZ, MU, MF, CX, MU, JL, KE, PA) don't seem to make all that much sense when they all fly to YVR (except HX), and YYZ has plenty of TPAC options. AF and KL, sure, but they only fly LHR to AMS and CDG respectively, which are already served extensively from Canada without the need for a stop at LHR. So, EK? Sure, it's possible. But they signed that codeshare 5 years ago, and WS still doesn't sell tickets to DXB or most of the places that EK flies, it's only EK selling tickets with connections on to WS flights. They do already codeshare the LGW flights, and EK flies to LGW. So is there really much value add in moving to LHR? Doesn't seem like it.

That's all well and good, but even if they sign a JV tomorrow, it will take quite some time to get antitrust blessing, and possibly longer before they actually implement it to any meaningful degree. AF and KL also don't provide any real connectivity from LHR, so on the topic of this thread, it would likely support more WS operations to AMS and CDG, but not LHR.

I'm not being critical of WS. Their philosophy is definitely slow and steady, and it has worked for them, so if they want to continue with that, it's fine. I just don't think flying to LHR really fits with that strategy any time soon.

AC was twice daily from YVR in the summer, once in winter. From YYC, we had a brief period where we had all three of AC, BA, and WS in the LON market, but WS seemed to be eating BA's lunch even before COVID. BA had temporarily suspended service when they encountered the RR engine problems on their 787 fleet a couple years ago, and I don't think they had ever resumed it. They announced last year that they were killing the route permanently. I won't miss their terrible hard product, but it's too bad to lose the great connections they offered.

But I think that's just more evidence for my point that LHR isn't such a huge selling point for traffic that's O/D London. If it were, why did WS's rise in the market so strongly correlate with BA's decline and exit?

Gatwick Express takes a bit longer than HEX, but it's not a huge difference. And Paddington vs Victoria isn't a big difference either, whether going to Mayfair or the City.

I don't see how your comments about FRA or AMS are relevant in this case (i.e. whether WS flies to LHR) though, since there's no way (on one ticket) to connect from WS to FRA at LHR, and AMS is already served direct by KL from YYC, YVR, etc.