Stay informed with free updatesSimply sign up to the UK property myFT Digest -- delivered directly to your inbox.Britain’s rental market faces “growing challenges” with rising demand and low supply, according to a closely watched survey that points to more pain for tenants as political parties focus on home ownership in the election campaign. The Royal Institution of Chartered Surveyors said on Thursday that its measure of tenant demand more than tripled to 35 in May from 10 in April. At the same time, new landlord instructions, which indicate landlords...