The Department for Transport has agreed to the first significant redesign of First Great Western's mainline timetable in Devon and Cornwall for over a decade, with earlier trains and extra capacity during the summer.
Looking just at Penzance, the first train from London Paddington leaves at 7.06 and currently arrives in Penzance at 12.43 (change at Newton Abbott). From Dec 2014 the train will be a through train arriving at approximately 12.03 ( 40 minutes earlier.)
There will also be increased capacity for summer travellers on the late morning (1039) service from Plymouth through Cornwall by using an eight carriage High Speed Train rather than a smaller local train.
The comparison in journey times between London - Newcastle and London - Penzance (both 300 miles) is dire; London – Newcastle fastest rail service is 2 hrs 47 mins (average ~3hrs 10 min) whereas for London-Penzance the fastest service is 5hrs 04 mins (average ~5 hrs 30 mins). The announcement does not solve the fundemental problem but is a welcome incremental improvement.