i was looking at another thread along the same lines and then remembered i might have to replace the mattress from my m&p herbie pram. i think the carry cot part is stored in the loft along with the mattress. do you think i need a new mattress. id never put db to sleep overnight in it i only want to walk around with him/her in the pram. i know a replacement will cost £25 from M&P and money is tight at the moment. would i be ok steam cleaning the mattress them putting a fitted sheet over it?