flying vancouver to rome via London, is 1.5 layover long enough?

Karen,

I'm assuming she'll be flying into LHR, perhaps with Air Canada / Lufthansa? That's a huge airport and in most cases 90 minutes should be adequate but a lot will depend on conditions at the time.

She will have to go through Passport control when she arrives. Last time I transited through there, I was required to have my photo taken at one of the security checkpoints. The agent then attached a small sticker to the back of my Passport and when I arrived at the security for my next flight, they scanned the sticker and my photo appeared on the monitor. For some reason, a few from my flight missed the photo part, and they had to go back and have their picture taken before they could proceed through security.

If the ticket is booked on a code share, her checked luggage should go directly to the final destination so she won't have to deal with that in London. Collecting checked luggage at FCO can sometimes be an "adventure". On one occasion, all the luggage from my Lufthansa connecting flight was directed to a Carousel in a different part of the airport and I was required to again go through the "dog & pony show* of security just to collect my bag off the Carousel. The *Lufthansa" staff seemed to be as confused as I was. Sometimes things in Italy don't always operate as expected, but I guess that makes for a memorable "holiday experience".

If the connecting flight is at Heathrow, be forewarned of how large the airport is. The terminals are pretty spread out. Everytime I have connected there, I need to take a bus to another terminal, go through security and then make my long jaunt to the gate. This will eat up some of your layover time. I would want at least a 2 hour layover there, jic my flight doesnt leave on time.

If she misses the connection, what is the cost?

The official minimum connect time for T5 to T5 between 2 international flights is 60 minutes. There is no need to go through immigration as this can be done airside but there will be a security checkpoint to negotiate. With a single ticket bags will be checked through to Rome. This assumes travel on a single ticket, which is implied by the journey description. In event of delay, eg inward flight being late the connecting flight would be switched to the next available.

Yes, if she misses her flight due to the first leg of the flight being late, she will be bumped to the next available flight at no charge.

What does it cost you if the first leg is "not sufficiently late" to make the airline responsible, but she misses anyway due to long lines or "airport congestion" or just not getting to the 2nd leg gate in time?
The question I don't know the answer to is, is whether travel insurance would take care of this?
And what's the next best alternative to the 90 minute layover?

Refund for missing a flight refund would probably be a question best answered by the company you bought the insurance from, but someone else may be able to answer that question for you. If not, you might try calling a couple of reliable travel insurance providers.

Marco gives sensible advice. If she misses the connection due to airport security delays etc BA will still put her on the next flight. BA rebook people all the time due to missed connections.

Thank you all, this is really helpful info. I didn't know about the Passport check aspect of the security screen upon arrival, but it makes sense and good to know about so I can warn her to be aware of what she needs to do when she changes planes. Will look into travel insurance to see exactly what it covers. I am glad she won't need to go thru immigration at Heathrow, and bags will be checked through to Rome. We haven't purchased the ticket yet, and so will keep my eyes out for a ticket with a little more time between connections as I hate for her to get stuck trying to solve a problem should she miss a connection, even if they would fairly easily get her on the next flight. Again, thanks for all of your input, very much appreciated!

Early afternoon is a relatively slack period for security - peak time is early morning. You may be able to get an itinerary with a longer connection time, but this is likely to be a bit more expensive with the onward flight then being early evening.

It is a good idea to see which sub-terminal the flight to Rome is leaving from checking from screens on arrival. Nearly all transatlantic flights arrive at B or C. Most European flights leave from A, but some leave from B (and more rarely from C). This is determined on a day to day basis. If she happens to arrive at the same sub-terminal as her departure, she does not need to go to the main security in A but can do it within the satellite.

You have to present yourself at security at least 35 minutes before departure.

At least 1 in 4 passengers in Terminal 5 are doing connections.