In OTL up to the leadership election of 1980 the leader of the Labour Party was elected by Labour MPs, so unless things have changed in this TL Ramsay MacDonald would not have handed over leadership of the party to George Lansbury or anyone else. Was Lansbury elected leader by Labour MPs? What is Arthur Henderson doing in this TL? I think he would be more likely to be elected Labour leader than Lansbury.
In the 1930 general election did the Liberal Party campaign on a policy of 'We Can Conquer Unemployment' as they did in the 1929 general election in OTL? Is Lloyd George leader of the Liberal Party?
In the 1930 general election with BNL (107 seats) plus Liberals (99 seats) and Labour (97 seats), making a total 303 seats, the maximum number of seats the Conservatives could win would be 615 less 303 = 312 seats. That is assuming no members of other parties or independents were elected.
Walter Elliot was a liberal and progressive Tory so most likely he would not be in a BNL Shadow Cabinet. Who was Oliver Russell? I have not found any relevant person with that name on Google. Vere Ponsonby was the 9th Earl of Bessborough:
http://en.wikipedia.org/wiki/Vere_Ponsonby,_9th_Earl_of_Bessborough . Charles Vane-Tempest-Stewart was the 7th Marquis of Londonderry.
What is the policy of the BNL regarding the League of Nations and recognition of the Soviet Union?
I would imagine that there is considerable sympathy on the right-wing of the Conservative Party towards the BNL. In the 1930 general election were there any pacts whereby in certain constituencies each party agreed to give the other a free run against Labour and/or the Liberals?