U.K. and Ireland - LGW to LHR 7am on Sat-3.5 hrs??

Ok folks - question for the experts. Have a transfer from LGW to LHR. Will be in business arriving on Delta and departing LHR on Kenya Airways. Will carry on a camera backpack and a slightly oversize (by UK standard) duffle. Hoping to be first off the plane from bus. class, breeze through passport control at 7am on a Saturday and head to a waiting car for transfer.

Issue-Will I have to check duffle at LHR for the onward flight? I was hoping to head through fast track at T4 with my slightly oversize duffle and just carry on. If I have to check I see no way to meet the 2 hr baggage check in window coming from LGW. Why is 3 hrs a legal connection if there is no way you can check your bags in if necessary and you cannot through check from LGW to LHR?

Any advice is appreciated. What are my chances of easing through fast track with my duffle and not having to check it?

Three questions...:

What's your nationality? (Even with a European Union passport you won't be "breezing" through passport control at 7 am when many of the transatlantic flights come in... but with a non-EU one you could be there for a long time!)

How oversized is your duffle?

How big is your camera bag?

Can you use fast track on a non BA itinerary? That is pushing it in my opinion-three hours to clear immigration, ride between airports, and still check-in in time? I wouldn't feel comfortable with less than 5.

I don't think you can fast track unless you are flying BA, but that may be incorrect.

We are travelling with US passports. I have heard that fast track for arriving flights is gone at LGA. Not sure if that is true or not. Was told that Delta Bus. class could use fast track when available.

Camera bag is regular bookbag backpack size. Duffle is 26x10x14 but will not be fully packed so will be "squishable".

Kenya Airways' carry-on limit is 56 x 36 x 20 cm (22.4 x 14.4 x 8 inches) with a weight limit of 10 kg, plus specified additional items the largest of which is a briefcase or laptop sized bag.

If you already have your BP then you'll be avoiding the one place where your carry-on is most likely to be sized and weighed, i.e., the check-in desk. They could still take it off you at the gate but I guess that won't really be an issue as you will have made your flight by then.

Don't have any knowledge of LGW Fastrack but have heard that even where Fastrack exists it is sometimes closed at the week-end, so I wouldn't rely on having the facility available. As a non-EU citizen you could have quite a long wait for Immigration.

As for the time you need to allow at LHR - unfortunately neither Kenya Airways' nor Heathrow's web site provide any information about the deadline for bag drop-off (as opposed to check-in). On my last long-haul flight from LHR (different airline, different terminal) I was told that the bag drop deadline was 90 minutes... which would give you two hours to get to LHR. It will all depend on the wait at Immigration... if it's no more than half an hour, and if there are no problems on the road, then you should be able to make it.