Trouble is the 757's are slowly disappearing from the fleet, and plan seems to be ultimately to keep 10-12 for the longer/busier routes from the largest bases - LGW, MAN, BHX, GLA. Assuming STN does well for TOM I wouldn't rule out a 3rd 738 in the next couple of years.
A little off topic but I also wonder if TCX would consider keeping one aircraft at STN over the winter for routes to places like ALC, AGP, Canaries, SSH, NBE, The Alps?