Equivalent of SystemCoreClock for LPC2388

I've got some code that was originally written for the LPC1768 which I am trying to "back-port" to the LPC2388

Most of that exercise was dealing with name changes, and was a (fairly) simple editing job.

Now however I have some code that reads:

		// Reset Timer 2
		T2TCR = 0x02;        
		T2TCR = 0x00;       // Timer mode, increment on PCLK

		// Calculate the match value based on the desired milliseconds delay
		uint32_t matchValue = (uint32_t)(((SystemCoreClock/1000) * millis) - 1);
		matchValue -= 50;	// Allow for the code in this function plus calling it

		T2MR0 = matchValue; // Set the match value

As you can see most of it has been converted already (e.g. LPC_TIM2->TCR became T2TCR).

How can I access the current clock speed value for the LPC2388 given that SystemCoreClock isn't defined anywhere in the 2388 headers etc..

Thanks, David