The 8 is just below, and partly overpainted by, the first "I" in Lusitania, the 8 or 9 is obscured by the end of the gun barrel and the "S", and the bottom of the 7 is just barely visible to the left of the 8 or 9 under the "U" .
P.S.: I've attached a bmp showing highlighting the numbers.
Frank Mitchell, MC, (of the first tank vs. tank battle fame) wrote an account of Lusitania's action on April 9, 1917, in his book "Tank Warfare" (1933, Nelson, London). The first attachment contains this excerpt. The map is a detail from Purnell's "History of the First World War" p. 2090 (1971), showing Lusitania's route. Briefly, after attacking the Railway Triangle and Feuchy Redoubt (despite mechanical problems), it was abandonned due to magneto failure in front of the British positions on the evening of the 9th. It was destroyed by the British barrage on the 10th, before the crew was able to return with a replacement. Lt. Weber was awarded the MC, and Sgt. Latham the MM.
Glad to help, Tim. "D" Battalion's war diary lists tank 798 as D.21, involoved in the Bullecourt attack on April 11. The attachment shows No. 11 Co.'s after action report, courtesy of the Tank Museum library.
Apologies for omitting the reference key to the chart; it is included in the first attachment. The second attachment is a map from p.314 of the Australian official history (C.E.W. Bean, The A.I.F. in France, Vol IV) showing wrecked tank positions at the end of the battle. Of the eleven tanks engaged, one was hit and disabled prior to starting, another soon after. Five were disabled in no-man's-land or the German trench system. Four tanks returned to the Australian front line, of which, two were disabled there and the other two disabled some distance to the rear.
Bean conducted extensive interviews and a review of German records after the war, and established that no tank reached the objectives of Riencourt and Hendrecourt; none had advanced past the second trench in the Hindenburg Line. Maj. W.H.L. Watson, of D. Co., wrote an account in his book "A Company of Tanks".
The 27th (Wurttemberg) Division had standing orders to concentrate their fire on tanks, and had been supplied with AP machine gun ammunition. The volume of fire which the tanks drew can be judged from participants' recollections of their shapes outlined in the darkness by sparks from bullet strikes.
As an aside, I suspect that tank 799, seen being inspected by Germans in a previous thread, is wreck "3", as it lay in the only portion of front not in British hands at battle's end. Due to a navigational error, it single-handedly attacked Balcony Trench near Queant, and was disabled behind the front line trench.
Lusitania was commanded by my Grandfather, at the time temporary Second Lieutenant Weber. The picture shown above is available from the Tank Museum at Bovingtnon ( http://www.tankmuseum.org/shop/photo.php?photo_id=9 ) As stated he received the MC for his actions at Railway Triangle. (and in fact later added an MBE )
I still have his sword, which I recently had refurbished to Horse Guards standard.
I seems my previous answer is still waiting for moderation, therefore I'll give it another try.
First of all, I'm glad you liked my project, since I really enjoyed researching and building it ( Lusitania, the roman province that gave place to my beautiful country, charismatic name to a charismatic tank).
As I found the photos online, I'm not able to give credit to it's owners. However, I can point you to versions with better resolution:
There is a very interesting section of C & A Williams-Ellis, 1919, The Tank Corps, New York page 99 to 103 describing the action carried out by Lt Webber and Sgt Latham of Lusitania at Arras in early April 1917.
The book can be accessed free online here: https://archive.org/stream/tankcorps00willgoog#page/n10/mode/2up
By the way, the Tank Corps didn't become 'Royal' until 18 October 1923. Good job on restoring his sword to Horse Guards standard, although I suspect he'd be turning in his grave at the thought of that. After all, he was a Tankie :)
Eyewitness, being personal reminiscences of certain phases of the Great War, including the genesis of the tank by Maj. Gen. Sir E D Swinton http://catalog.hathitrust.org/Record/000442267