May be this is true or may be it's an urban myth! However I promised Steve that I would tell him the story I heard in a pub once when out with the lads after a main line jolly, so here it is.
Apparently when the Funny Farm (Derby Research Centre) was developing the HST and APT prototypes there arose the question of what would happen if a large bird was hit by the trains at high speed. A junior boffin was dispatched to the supermarket to buy some chickens. These were then propelled at great velocity into various examples of windscreen glass.
It so happened that the outcome of the trials was a windscreen that withstood the impact safely, and this was used on the actual cab.
Now the good bit

. We were told that a certain other country (about 3000 miles west of Derby) decided to test some of their loco windscreens. Every one failed miserably. After much scratching of heads and chewing of pencils somebody suggested thawing out the chickens before carrying out the experiment!
John