I think it's probably correct to say that the current deal is just to cover the next couple of months of increased bizjet activity/demand (if that actually happens), although whether both parties see it leading to a long term agreement I don't know. Possibly Landmark see an opportunity here to expand into the UK market.
The good news for SEN though is that they will now have a high quality, dedicated FBO facility and a major player in that market has endorsed that fact. I'm sure that Andrew Tinkler will have had a major say in the facilities that are being provided and I just cannot see him settling for second best in terms of quality - he knows what he expects elsewhere for his F900 handling.
It's all due for final completion in about 10 days time when, hopefully, some photographs will become available.