A cascade of purple and pink hydrangea, wisteria and fresh sea lavender lined the walls of the carriage filling the air with the aroma of fresh spring blossom.
More than 3,000 flowers in total were installed on the 43 seat, 23-metre long carriage.
Heathrow Express commissioned the on-board flower show to celebrate the 2019 RHS Chelsea Flower Show.
A spokesperson for Heathrow Express said: “The duration of our transfer service is just 15 minutes so we wanted to make an instant impression on customers departing from and arriving in the UK.
“The Chelsea Flower Show is one of the biggest events of the year but not everyone gets the chance to experience it so we wanted to give travellers a little taster.
“And we’re delighted to say the reaction of customers has been blooming marvellous.”
The ‘flower express’ display, which was created by London-based Jamie Aston Flowers, featured 1,850 hydrangeas, 220 wisterias and 1,000 stems of fresh sea lavender.
The mix of real and artificial flowers were attached to the ceiling and walls using suction grips and hooks and the plants in the luggage racks were held in place by foam.
And it took the eight-person team four hours to install – and several months of planning.
Around 18,000 passengers are expected to use the transfer service today across its 150 journeys.
Jamie Aston said: “We’ve created all manner of flower displays but have never had the chance to create one on board a train.
“We wanted to create something which would bring a smile to passengers’ faces and help them to unwind ahead or following their flight.”
For a chance to win two tickets to the RHS Chelsea Flower Show on Saturday 25 May, 2019 share your snaps of the flower carriage on Twitter or Instagram tagging in @Heathrowexpress and using #FlowerExpress.
The competition closes at midnight on Wednesday 22 May 2019.
And Heathrow Express customers will have until Wednesday 22 May 2019 to experience the flower express installation.