The Four-Headed Buddha

One of the things that intrigued me on my recent trip was the presence of shrines to Phra Phrom throughout Hong Kong and Macau. Visitors to Thailand would be familiar with this deity, a Thai representation of Brahma, the creator god of Hinduism. His presence in Thailand is everywhere (most notably at the Erawan Shrine, one of my favourite places in Bangkok), and understandably given Thailand's Hindu past and the continued presence of Hindu spirituality there. But why are these shrines popping up in Hong Kong and Macau? Is there some historical presence of this Hindu deity in popular Chinese religion that I have been unaware of? Have the shrines been constructed by expatriate Thai working in the enormous service sectors of those countries? Surely they don't have the political pull or social organisation to manage such a large-scale project? They are all too busy working. Have they been erected by wealthy Thai-Chinese with business or family interests in Hong Kong?
I'd really love to know - it's a fascinating phenomenon. However they got there, the shrines seem to be well patronised by average Chinese people, though the lay-out is of a conventionally Thai fashion.
Here is a pic of one of these shrines outside Che Kung Temple in Hong Kong.