Well actually there is a chance Thomson will have a 787 at cardiff in the future as there is plans for major improvements to Cardiff airport to be a international hub for Heathrow.
"Cardiff Airport: Western Gateway plan for Heathrow hub.
Ambitious plans to transform Cardiff Airport into an international hub have been submitted to the UK government.
Transport experts and entrepreneurs have developed a £250m plan to turn it into Heathrow's Atlantic terminal.
An expanded Cardiff Airport, to be called Western Gateway, aims to attract international fliers who can be transported to London via high speed rail within an hour. "
Although thomson do not fly from LHR thomson will be having competition will all the other airlines that would be in Cardiff so there is a high chance they will base an 787.