Between 1918 and 1919 there was a Anglo-Indian force of some thousands in modern day Turkmenistan lead by General Wilfrid Malleson (one of the last players of the Great Game). This force had many names (the East Persian Cordon was one as was the Malleson Mission) but its ostensible job was to: "combat German and Turkish propaganda and attempts to organise men, railways and resources towards assisting hostile enterprises, aggression or active operations against us or our Allies. In reality what this very much amounted to was combatting the local Bolshevik forces on the ground much as another British force was doing in Vladivostok.
Malleson fought several battles with the 'Bolos' near and around Ashkabad and won each of them inflicting grievous casualties. Rumours were put about (mostly by Malleson's own agents) that he intended to march on the Soviet Central Asian capital of Tashkent, so convincing were these rumours that British secret agents inside the city broke their cover in order to inform him how best to assault the city, additionally Damagatsky, the Soviet Commisionar for Foreign Affairs in Tashkent put out feelers about obtaining political asylum.
Now my question is this, considering how frail the Bolshevik rule was in Central Asia at the time, that there were several White Russian leaders in the area, that the Bolshevik's were at this time cut off from reinforcements, that the British force totally outclassed the Bolshevik's and they could and did draw on local anti-revolutionary elements, what happens if Malleson assaults and takes Tashkent routing the Soviets in Southern Central Asia?
My thoughts are thus: if those in charge in India don't recall Malleson when they realised he had overstepped his mark (his orders contained nothing about capturing territory slightly larger than Egypt) that you could end up with British/White Russian/Turkman protectorate stretching from Ashkabad in Turkmenistan to Kashgar in Xinjiang to Tashkent in Uzebekistan (perhaps even spreading into Kazakhstan or the Caspian Sea). Certainly the British had the ability to do it, were backed up by the natives and had the support of Afghanistan. As for the long term repercussions I would be intrested to hear your thoughts.