Clarkson's father in law using a mortar as an impromtu anti-tank gun?
Close but not quite. Clarkson's father in law - Major Robert Cain was a company commander in the 2nd Battalion South Staffords. His most famous exploits took place in the Osterbeek Perimeter, although he was also involved in some fighting around the St Elizabeth Hospital beforehand. Neither he nor the men in his command ever reached the bridge itself.
I was thinking more of men like Major Tatham-Warter of "A" Company, 2nd Parachute Battalion. He was the man who went about his duties at the bridge carrying an umbrella and wearing either a red beret or bowler hat. He apparently reasoned that they'd help identify him in battle since only a mad fool of an Englishman would be kitted out that way for a battle.
He's also supposed to have made an amusing reply at one point which was repeated in A Bridge Too Far, albeit under the guise of Major Carlyle. Bear in mind that this is at a point in the fighting where the small British para force is surrounded, cut off from reinforcements and under attack from tanks, infantry and artillery.
[an SS officer is approaching under a flag of truce] Major Harry Carlyle: Rather interesting development, sir.
[to the German] Major Harry Carlyle: That's far enough!
Major Harry Carlyle: We can hear you from there!
SS Panzer Officer: My general says there is no point in continuing this fighting! He wishes to discuss terms of a surrender!
Major Harry Carlyle: Shall I answer him, sir?
Lt. Col. John Frost: Tell him to go to hell.
Major Harry Carlyle: We haven't the proper facilities to take you all prisoner! Sorry!
[German officer looks confused] SS Panzer Officer: What?
Major Harry Carlyle: We'd like to, but we can't accept your surrender! Was there anything else?
[German officer walks off] Lt. Col. John Frost: Well; that's that.
[in German] SS Panzer Officer: They rejected our surrender offer. What are your orders, Herr General?
[in German] Lt. General Bittrich: Flatten Arnhem.
Good old British humour shining through at even the worst of times.
