Just for information: when I visited and fotographed the Gresley at the Grosmont workt (North Yorkshire, England) the boiler was being drained for some minor maintenance. Which explains the red warning sign 'boiler empty'.
And if readers are interested at the complete overhaul (down to the last nut 'n bolt): go to
Sir Nigel Gresley overhaul - introduction - National Railway Museum blog. You will find a list of monthly reports on the right, under 'Archives'. Highley recommended.
One picture shows the right hand frame being tested; the other shows the boiler on transport through the medieval town of York (where the large railway museum is situated), on its way to Llangollen in Wales for the next stage of the overhaul.
(And yes, the cars are on the wrong side of the road...)