Basic problem: if security is such a looming issue and we feel the need for a revamp, then I think that troop no. would be one of the last places to start. First of all, we would look at upgrading the technology and numbers (of machines or the 'weapons of war') of both the Navy and the Airforce (ie constructing large groups of ac carriers, subs, better fighter planes etc and in larger numbers). Naturally, we would then look to acquiring the necessary numbers to man / fly / operate these pieces of technology. Many of these are specialist, which would make conscription undesirable and probably ineffectual; and I doubt it would be a necessity for fulfilling the required no.
We would then look to developing a decent and largely independant (or at least capable of indepedance if the situation called for it) war industry - aim at the long term production of our own munitions, ammo, uniforms, weapons, vehicles, etc. Furthermore, we would aim to expand (as before) our own engineering areas which relate to the design of such devices.
Once we came to the army, if we really wanted to improve it, we would look to upgrading our armour no. and level of technological advancement. Then, possibly then, we would come to the issue of troop numbers - we have a fair distance to go before we even need to consider conscription. As it stands, simply increasing the number of troops would do very little in a modern war (even though the army is still essential). A mass of bodies are not going to defend against against nukes or standard cruise/ballistic missiles (indeed, if we regarded this as a seroius threat, we would begin to look to developing effective counter active defensive systems instead). And it would work far better if we developed a better method of persuading a larger number of people that entering the army/ other armed branch was desirable in not only a personal and fiscal level, but also on a wider cultural level, rather than violating our national principles by forcing people to fight. Also persuading soldiers to stay in the army a long time after their minimum service time has expired would also assist (ie maintaining a strong veteran base). Conscription would also fail simply because the public would reject it and try at every term to undermine it. It would not make a noteworthy difference.
