Waterloo station was scheduled to open 30th June 1848, but Inspector rejected the quality of the track on 28th
After hasty track improvements, it opened formally 11th July 1848, but first train was arrival of night mail early on 13th July
Rather fitting they use a 701 to 'celebrate' a station opening date without trains (so couldn't be used), as 701s are trains that aren't yet open to use, so parking one in Waterloo out of use is rather cool (or ironic, delete as appropriate)
Bit of a shame didn't then start 701 service from Waterloo on 13th to match the 175th anniversary of trains running.